<?xml version="1.0" encoding="UTF-8"?>
<!--XBRL Document Modified with Ez-Editor Version 1.1.0.1 on Tuesday, August 12, 2014 04:06:43 AM -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#SummaryOfSignificantAccountingPoliciesDetails1" roleURI="http://www.cyclacel.com/role/SummaryOfSignificantAccountingPoliciesDetails1"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#FairValueDetails" roleURI="http://www.cyclacel.com/role/FairValueDetails"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#FairValueDetails1" roleURI="http://www.cyclacel.com/role/FairValueDetails1"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#FairValueDetails2" roleURI="http://www.cyclacel.com/role/FairValueDetails2"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#FairValueDetails3" roleURI="http://www.cyclacel.com/role/FairValueDetails3"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#StockBasedCompensationDetails" roleURI="http://www.cyclacel.com/role/StockBasedCompensationDetails"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#StockBasedCompensationDetails1" roleURI="http://www.cyclacel.com/role/StockBasedCompensationDetails1"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#StockBasedCompensationDetails2" roleURI="http://www.cyclacel.com/role/StockBasedCompensationDetails2"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#StockBasedCompensationDetails3" roleURI="http://www.cyclacel.com/role/StockBasedCompensationDetails3"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#StockBasedCompensationDetails4" roleURI="http://www.cyclacel.com/role/StockBasedCompensationDetails4"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#StockBasedCompensationDetails5" roleURI="http://www.cyclacel.com/role/StockBasedCompensationDetails5"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#StockholdersEquityDetails" roleURI="http://www.cyclacel.com/role/StockholdersEquityDetails"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#StockholdersEquityDetails2" roleURI="http://www.cyclacel.com/role/StockholdersEquityDetails2"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#Stockholdersequitydetails3" roleURI="http://www.cyclacel.com/role/Stockholdersequitydetails3"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#Stockholdersequitydetails4" roleURI="http://www.cyclacel.com/role/Stockholdersequitydetails4"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#Stockholdersequitydetails5" roleURI="http://www.cyclacel.com/role/Stockholdersequitydetails5"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#Stockholdersequitydetails6" roleURI="http://www.cyclacel.com/role/Stockholdersequitydetails6"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#DiscontinuedOperationsDetails" roleURI="http://www.cyclacel.com/role/DiscontinuedOperationsDetails"/>
<roleRef xlink:type="simple" xlink:href="cycc-20140630.xsd#DiscontinuedOperationsDetails2" roleURI="http://www.cyclacel.com/role/DiscontinuedOperationsDetails2"/>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/SummaryOfSignificantAccountingPoliciesDetails1">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_0" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConvertiblePreferredStockMember" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember_6" order="20" use="optional"/>


<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaap_WarrantMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_3" xlink:to="loc_us-gaap_WarrantMember_8" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_0" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_9" order="10" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/FairValueDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_3" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_10" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_11" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashEquivalentsAtCarryingValue_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_11" xlink:to="loc_us-gaap_CashEquivalentsAtCarryingValue_12" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_FinancialInstrumentAssociatedWithStockPurchaseAgreementFairValueDisclosure" xlink:label="loc_cycc_FinancialInstrumentAssociatedWithStockPurchaseAgreementFairValueDisclosure_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_11" xlink:to="loc_cycc_FinancialInstrumentAssociatedWithStockPurchaseAgreementFairValueDisclosure_13" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_11" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_14" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_15" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_OtherLiabilitiesFairValueAbstract" xlink:label="loc_cycc_OtherLiabilitiesFairValueAbstract_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_15" xlink:to="loc_cycc_OtherLiabilitiesFairValueAbstract_16" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GuaranteesFairValueDisclosure" xlink:label="loc_us-gaap_GuaranteesFairValueDisclosure_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_OtherLiabilitiesFairValueAbstract_16" xlink:to="loc_us-gaap_GuaranteesFairValueDisclosure_17" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherLiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_OtherLiabilitiesFairValueDisclosure_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_OtherLiabilitiesFairValueAbstract_16" xlink:to="loc_us-gaap_OtherLiabilitiesFairValueDisclosure_18" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_15" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_19" order="10" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/FairValueDetails1">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_0" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_1" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_2" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_2" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GuaranteesMember" xlink:label="loc_us-gaap_GuaranteesMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3" xlink:to="loc_us-gaap_GuaranteesMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_0" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_5" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_5" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_7" order="10" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/FairValueDetails2">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_2" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_2" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EconomicRightsMember" xlink:label="loc_cycc_EconomicRightsMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3" xlink:to="loc_cycc_EconomicRightsMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_AgreementAxis" xlink:label="loc_cycc_AgreementAxis_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" xlink:to="loc_cycc_AgreementAxis_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_AgreementDomain" xlink:label="loc_cycc_AgreementDomain_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cycc_AgreementAxis_5" xlink:to="loc_cycc_AgreementDomain_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_AgreementDomain" xlink:label="loc_cycc_AgreementDomain_6_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cycc_AgreementAxis_5" xlink:to="loc_cycc_AgreementDomain_6_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PurchaseAgreementMember" xlink:label="loc_cycc_PurchaseAgreementMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_AgreementDomain_6" xlink:to="loc_cycc_PurchaseAgreementMember_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_DefinitiveAgreementMember" xlink:label="loc_cycc_DefinitiveAgreementMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_AgreementDomain_6" xlink:to="loc_cycc_DefinitiveAgreementMember_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationCaseAxis" xlink:label="loc_us-gaap_LitigationCaseAxis_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" xlink:to="loc_us-gaap_LitigationCaseAxis_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationCaseTypeDomain" xlink:label="loc_us-gaap_LitigationCaseTypeDomain_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationCaseAxis_9" xlink:to="loc_us-gaap_LitigationCaseTypeDomain_10" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationCaseTypeDomain" xlink:label="loc_us-gaap_LitigationCaseTypeDomain_10_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationCaseAxis_9" xlink:to="loc_us-gaap_LitigationCaseTypeDomain_10_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_CelgeneCorporationCaseMember" xlink:label="loc_cycc_CelgeneCorporationCaseMember_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationCaseTypeDomain_10" xlink:to="loc_cycc_CelgeneCorporationCaseMember_11" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1" xlink:to="loc_dei_LegalEntityAxis_12" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_12" xlink:to="loc_dei_EntityDomain_13" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_13_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_12" xlink:to="loc_dei_EntityDomain_13_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_AspireCapitalFundLLCMember" xlink:label="loc_cycc_AspireCapitalFundLLCMember_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_13" xlink:to="loc_cycc_AspireCapitalFundLLCMember_14" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForCash" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesIssuedForCash_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesIssuedForCash_15" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForCash" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForCash_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForCash_16" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_CommonStockPurchaseAgreementShares" xlink:label="loc_cycc_CommonStockPurchaseAgreementShares_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_cycc_CommonStockPurchaseAgreementShares_17" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_CommonStockPurchaseAgreementTermPeriod" xlink:label="loc_cycc_CommonStockPurchaseAgreementTermPeriod_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_cycc_CommonStockPurchaseAgreementTermPeriod_18" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ReceivablesFairValueDisclosure" xlink:label="loc_us-gaap_ReceivablesFairValueDisclosure_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_ReceivablesFairValueDisclosure_19" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DerivativeGainLossOnDerivativeNet" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_20"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_20" order="60" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/FairValueDetails3">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GuaranteeObligationsLineItems" xlink:label="loc_us-gaap_GuaranteeObligationsLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfGuaranteeObligationsTable" xlink:label="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_0" xlink:to="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GuaranteeObligationsByNatureAxis" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_1" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_2" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_2" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PerformanceGuaranteeMember" xlink:label="loc_us-gaap_PerformanceGuaranteeMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_3" xlink:to="loc_us-gaap_PerformanceGuaranteeMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GuaranteeObligationsMaximumExposure" xlink:label="loc_us-gaap_GuaranteeObligationsMaximumExposure_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_0" xlink:to="loc_us-gaap_GuaranteeObligationsMaximumExposure_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_GuarantorObligationsModifiedPaymentForWhichPartiesAgreed" xlink:label="loc_cycc_GuarantorObligationsModifiedPaymentForWhichPartiesAgreed_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_0" xlink:to="loc_cycc_GuarantorObligationsModifiedPaymentForWhichPartiesAgreed_6" order="20" use="optional"/>


<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_GuarantorObligationsAmountPaid" xlink:label="loc_cycc_GuarantorObligationsAmountPaid_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_0" xlink:to="loc_cycc_GuarantorObligationsAmountPaid_8" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_GuarantorObligationsPotentialAmountToBePaidIfStaffingLevelsReducedBelowPrescribedLevels" xlink:label="loc_cycc_GuarantorObligationsPotentialAmountToBePaidIfStaffingLevelsReducedBelowPrescribedLevels_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_0" xlink:to="loc_cycc_GuarantorObligationsPotentialAmountToBePaidIfStaffingLevelsReducedBelowPrescribedLevels_9" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GuaranteesFairValueDisclosure" xlink:label="loc_us-gaap_GuaranteesFairValueDisclosure_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_0" xlink:to="loc_us-gaap_GuaranteesFairValueDisclosure_10" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_0" xlink:to="loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate_11" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_FairValueAssumptionsProbabilityOfFallingStaffingLevelBelowMinimumPrescribedLevelsWithinPrescribedTimePeriod" xlink:label="loc_cycc_FairValueAssumptionsProbabilityOfFallingStaffingLevelBelowMinimumPrescribedLevelsWithinPrescribedTimePeriod_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_0" xlink:to="loc_cycc_FairValueAssumptionsProbabilityOfFallingStaffingLevelBelowMinimumPrescribedLevelsWithinPrescribedTimePeriod_12" order="80" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/StockBasedCompensationDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" xlink:to="loc_us-gaap_TitleOfIndividualAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_2" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_2" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ExecutiveOfficerMember" xlink:label="loc_us-gaap_ExecutiveOfficerMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_3" xlink:to="loc_us-gaap_ExecutiveOfficerMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" xlink:to="loc_us-gaap_RangeAxis_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_5" xlink:to="loc_us-gaap_RangeMember_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_6_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_5" xlink:to="loc_us-gaap_RangeMember_6_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_6" xlink:to="loc_us-gaap_MinimumMember_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_6" xlink:to="loc_us-gaap_MaximumMember_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_9" order="10" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/StockBasedCompensationDetails1">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_2" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_2" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_6" order="10" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/StockBasedCompensationDetails2">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" xlink:to="loc_us-gaap_AwardTypeAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_7" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_5" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_8" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_9" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_5" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_10" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_11" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_12" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_12" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_13" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_12" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_14" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_12" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_15" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_12" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_16" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedWeightedAverageExercisePrice" xlink:label="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedWeightedAverageExercisePrice_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_12" xlink:to="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedWeightedAverageExercisePrice_17" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_12" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_18" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" xlink:label="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_19" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_20"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_19" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_20" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedWeightedAverageRemainingContractualTerm" xlink:label="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedWeightedAverageRemainingContractualTerm_21"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_19" xlink:to="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedWeightedAverageRemainingContractualTerm_21" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_22"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_19" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_22" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIntrinsicValueAbstract" xlink:label="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIntrinsicValueAbstract_23"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIntrinsicValueAbstract_23" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_24"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIntrinsicValueAbstract_23" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_24" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedIntrinsicValue" xlink:label="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedIntrinsicValue_25"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIntrinsicValueAbstract_23" xlink:to="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedIntrinsicValue_25" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_26"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIntrinsicValueAbstract_23" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_26" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/StockBasedCompensationDetails3">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" xlink:to="loc_us-gaap_AwardTypeAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_6" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_7" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_8" order="40" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/StockBasedCompensationDetails4">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" xlink:to="loc_us-gaap_AwardTypeAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_10" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_10" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_11" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_10" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_12" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_10" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_13" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/StockBasedCompensationDetails5">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" xlink:to="loc_us-gaap_AwardTypeAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1" xlink:to="loc_us-gaap_RangeAxis_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_6" xlink:to="loc_us-gaap_RangeMember_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_7_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_6" xlink:to="loc_us-gaap_RangeMember_7_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_7" xlink:to="loc_us-gaap_MinimumMember_8" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_7" xlink:to="loc_us-gaap_MaximumMember_9" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_10" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeitureRate" xlink:label="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeitureRate_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_10" xlink:to="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeitureRate_11" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsNumberOfSecuritiesUsedToCalculateWeightedAverageRiskFreeInterestRate" xlink:label="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsNumberOfSecuritiesUsedToCalculateWeightedAverageRiskFreeInterestRate_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_10" xlink:to="loc_cycc_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsNumberOfSecuritiesUsedToCalculateWeightedAverageRiskFreeInterestRate_12" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_10" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_13" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/StockholdersEquityDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockRedemptionPeriodAxis" xlink:label="loc_cycc_PreferredStockRedemptionPeriodAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1" xlink:to="loc_cycc_PreferredStockRedemptionPeriodAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockRedemptionPeriodDomain" xlink:label="loc_cycc_PreferredStockRedemptionPeriodDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cycc_PreferredStockRedemptionPeriodAxis_2" xlink:to="loc_cycc_PreferredStockRedemptionPeriodDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockRedemptionPeriodDomain" xlink:label="loc_cycc_PreferredStockRedemptionPeriodDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cycc_PreferredStockRedemptionPeriodAxis_2" xlink:to="loc_cycc_PreferredStockRedemptionPeriodDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockRedemptionPeriodFromYear1November2013To31October2014Member" xlink:label="loc_cycc_PreferredStockRedemptionPeriodFromYear1November2013To31October2014Member_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_PreferredStockRedemptionPeriodDomain_3" xlink:to="loc_cycc_PreferredStockRedemptionPeriodFromYear1November2013To31October2014Member_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockRedemptionPeriodFromYear1November2014AndThereafterMember" xlink:label="loc_cycc_PreferredStockRedemptionPeriodFromYear1November2014AndThereafterMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_PreferredStockRedemptionPeriodDomain_3" xlink:to="loc_cycc_PreferredStockRedemptionPeriodFromYear1November2014AndThereafterMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockRedemptionPricePerShare" xlink:label="loc_us-gaap_PreferredStockRedemptionPricePerShare_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_PreferredStockRedemptionPricePerShare_6" order="10" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/StockholdersEquityDetails2">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConvertiblePreferredStockMember" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonStockMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1" xlink:to="loc_us-gaap_RangeAxis_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_6" xlink:to="loc_us-gaap_RangeMember_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_7_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_6" xlink:to="loc_us-gaap_RangeMember_7_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_7" xlink:to="loc_us-gaap_MinimumMember_8" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_PreferredStockSharesIssued_9" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_10" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_11" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockDividendRatePercentage" xlink:label="loc_us-gaap_PreferredStockDividendRatePercentage_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_PreferredStockDividendRatePercentage_12" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PreferredStockLiquidationPreference" xlink:label="loc_us-gaap_PreferredStockLiquidationPreference_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_PreferredStockLiquidationPreference_13" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockConvertibleConversionRatio" xlink:label="loc_cycc_PreferredStockConvertibleConversionRatio_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_PreferredStockConvertibleConversionRatio_14" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ConvertiblePreferredStockConversionPricePerShare" xlink:label="loc_cycc_ConvertiblePreferredStockConversionPricePerShare_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_ConvertiblePreferredStockConversionPricePerShare_15" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_16" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_NumberOfSeriesOfPreferredStock" xlink:label="loc_cycc_NumberOfSeriesOfPreferredStock_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_NumberOfSeriesOfPreferredStock_17" order="90" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaap_SharePrice_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_SharePrice_18" order="100" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockConversionObligationCommonStockClosingSalesPriceAsPercentageOfConversionPrice" xlink:label="loc_cycc_PreferredStockConversionObligationCommonStockClosingSalesPriceAsPercentageOfConversionPrice_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_PreferredStockConversionObligationCommonStockClosingSalesPriceAsPercentageOfConversionPrice_19" order="110" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockConversionObligationCommonStockClosingSalesPriceNumberOfTradingDays" xlink:label="loc_cycc_PreferredStockConversionObligationCommonStockClosingSalesPriceNumberOfTradingDays_20"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_PreferredStockConversionObligationCommonStockClosingSalesPriceNumberOfTradingDays_20" order="120" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockConversionObligationNumberOfTradingDays" xlink:label="loc_cycc_PreferredStockConversionObligationNumberOfTradingDays_21"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_PreferredStockConversionObligationNumberOfTradingDays_21" order="130" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockConversionObligationThirtyDayTradingPeriodEndingWithinNumberOfTradingDaysPriorToNoticeOfAutomaticConversion" xlink:label="loc_cycc_PreferredStockConversionObligationThirtyDayTradingPeriodEndingWithinNumberOfTradingDaysPriorToNoticeOfAutomaticConversion_22"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_PreferredStockConversionObligationThirtyDayTradingPeriodEndingWithinNumberOfTradingDaysPriorToNoticeOfAutomaticConversion_22" order="140" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockNumberOfQuartersInWhichCashDividendsNotPaid" xlink:label="loc_cycc_PreferredStockNumberOfQuartersInWhichCashDividendsNotPaid_23"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_PreferredStockNumberOfQuartersInWhichCashDividendsNotPaid_23" order="150" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_NumberOfBoardOfDirectorsToBeElectedByPreferredStockHoldersUponFailureToPayDividendsOnPreferredStock" xlink:label="loc_cycc_NumberOfBoardOfDirectorsToBeElectedByPreferredStockHoldersUponFailureToPayDividendsOnPreferredStock_24"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_NumberOfBoardOfDirectorsToBeElectedByPreferredStockHoldersUponFailureToPayDividendsOnPreferredStock_24" order="160" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_NumberOfBoardOfDirectorsElectedByPreferredStockHoldersDueToFailureToPayDividendsOnPreferredStock" xlink:label="loc_cycc_NumberOfBoardOfDirectorsElectedByPreferredStockHoldersDueToFailureToPayDividendsOnPreferredStock_25"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_NumberOfBoardOfDirectorsElectedByPreferredStockHoldersDueToFailureToPayDividendsOnPreferredStock_25" order="170" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_26"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_26" order="180" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_PreferredStockExchangeRatePrincipalAmountOfNotesUsedInCalculation" xlink:label="loc_cycc_PreferredStockExchangeRatePrincipalAmountOfNotesUsedInCalculation_27"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_PreferredStockExchangeRatePrincipalAmountOfNotesUsedInCalculation_27" order="190" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaap_DebtInstrumentTerm_28"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_DebtInstrumentTerm_28" order="200" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1_29"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1_29" order="210" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_30"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_30" order="220" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_RedeemablePreferredStocksDividends" xlink:label="loc_cycc_RedeemablePreferredStocksDividends_31"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_RedeemablePreferredStocksDividends_31" order="230" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/Stockholdersequitydetails3">
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingLineItems" xlink:label="loc_cycc_EquityOfferingLineItems_0"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingTable" xlink:label="loc_cycc_EquityOfferingTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_EquityOfferingTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cycc_EquityOfferingTable_1" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2" xlink:to="loc_us-gaap_EquityComponentDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2" xlink:to="loc_us-gaap_EquityComponentDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3" xlink:to="loc_us-gaap_CommonStockMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentsAxis" xlink:label="loc_cycc_EquityOfferingComponentsAxis_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cycc_EquityOfferingTable_1" xlink:to="loc_cycc_EquityOfferingComponentsAxis_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentDomain" xlink:label="loc_cycc_EquityOfferingComponentDomain_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cycc_EquityOfferingComponentsAxis_5" xlink:to="loc_cycc_EquityOfferingComponentDomain_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentDomain" xlink:label="loc_cycc_EquityOfferingComponentDomain_6_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cycc_EquityOfferingComponentsAxis_5" xlink:to="loc_cycc_EquityOfferingComponentDomain_6_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_April2014IssuanceMember" xlink:label="loc_cycc_April2014IssuanceMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_6" xlink:to="loc_cycc_April2014IssuanceMember_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SharesIssuedPricePerShare" xlink:label="loc_us-gaap_SharesIssuedPricePerShare_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_SharesIssuedPricePerShare_10" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_11" order="40" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/Stockholdersequitydetails4">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2" xlink:to="loc_us-gaap_ClassOfStockDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConvertiblePreferredStockMember" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3" xlink:to="loc_us-gaap_CommonStockMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ConversionOfConvertiblePreferredStockAbstract" xlink:label="loc_cycc_ConversionOfConvertiblePreferredStockAbstract_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0" xlink:to="loc_cycc_ConversionOfConvertiblePreferredStockAbstract_6" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ConversionOfConvertiblePreferredStockAbstract_6" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1_7" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_CommonStockIssuedAbstract" xlink:label="loc_cycc_CommonStockIssuedAbstract_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ConversionOfConvertiblePreferredStockAbstract_6" xlink:to="loc_cycc_CommonStockIssuedAbstract_8" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_StockIssuedDuringPeriodSharesConversionOfConvertibleSecuritiesAtStatedConvertibleOption" xlink:label="loc_cycc_StockIssuedDuringPeriodSharesConversionOfConvertibleSecuritiesAtStatedConvertibleOption_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_CommonStockIssuedAbstract_8" xlink:to="loc_cycc_StockIssuedDuringPeriodSharesConversionOfConvertibleSecuritiesAtStatedConvertibleOption_9" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_StockIssuedDuringPeriodSharesConversionOfConvertibleSecuritiesIncrementalShares" xlink:label="loc_cycc_StockIssuedDuringPeriodSharesConversionOfConvertibleSecuritiesIncrementalShares_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_CommonStockIssuedAbstract_8" xlink:to="loc_cycc_StockIssuedDuringPeriodSharesConversionOfConvertibleSecuritiesIncrementalShares_10" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_CommonStockIssuedAbstract_8" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_11" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/Stockholdersequitydetails5">
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingLineItems" xlink:label="loc_cycc_EquityOfferingLineItems_0"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingTable" xlink:label="loc_cycc_EquityOfferingTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_EquityOfferingTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentsAxis" xlink:label="loc_cycc_EquityOfferingComponentsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cycc_EquityOfferingTable_1" xlink:to="loc_cycc_EquityOfferingComponentsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentDomain" xlink:label="loc_cycc_EquityOfferingComponentDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cycc_EquityOfferingComponentsAxis_2" xlink:to="loc_cycc_EquityOfferingComponentDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentDomain" xlink:label="loc_cycc_EquityOfferingComponentDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cycc_EquityOfferingComponentsAxis_2" xlink:to="loc_cycc_EquityOfferingComponentDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_November2013StockIssuanceMember" xlink:label="loc_cycc_November2013StockIssuanceMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_November2013StockIssuanceMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_December2012StockIssuanceMember" xlink:label="loc_cycc_December2012StockIssuanceMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_December2012StockIssuanceMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_May2013SaleOfCommonStockMember" xlink:label="loc_cycc_May2013SaleOfCommonStockMember_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_May2013SaleOfCommonStockMember_6" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_March2012SaleOfCommonStockAndEconomicRightsMember" xlink:label="loc_cycc_March2012SaleOfCommonStockAndEconomicRightsMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_March2012SaleOfCommonStockAndEconomicRightsMember_7" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_July2011StockIssuanceMember" xlink:label="loc_cycc_July2011StockIssuanceMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_July2011StockIssuanceMember_8" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_October2010StockIssuanceMember" xlink:label="loc_cycc_October2010StockIssuanceMember_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_October2010StockIssuanceMember_9" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_January2010StockIssuanceOneMember" xlink:label="loc_cycc_January2010StockIssuanceOneMember_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_January2010StockIssuanceOneMember_10" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_January2010StockIssuanceTwoMember" xlink:label="loc_cycc_January2010StockIssuanceTwoMember_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_January2010StockIssuanceTwoMember_11" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_July2009StockIssuanceMember" xlink:label="loc_cycc_July2009StockIssuanceMember_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_July2009StockIssuanceMember_12" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cycc_EquityOfferingTable_1" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_13" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_13" xlink:to="loc_us-gaap_EquityComponentDomain_14" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_14_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_13" xlink:to="loc_us-gaap_EquityComponentDomain_14_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_15"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_14" xlink:to="loc_us-gaap_CommonStockMember_15" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaap_WarrantMember_16"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_14" xlink:to="loc_us-gaap_WarrantMember_16" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_17"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cycc_EquityOfferingTable_1" xlink:to="loc_us-gaap_RangeAxis_17" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_18"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_17" xlink:to="loc_us-gaap_RangeMember_18" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_18_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_17" xlink:to="loc_us-gaap_RangeMember_18_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_19"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_18" xlink:to="loc_us-gaap_MaximumMember_19" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_20"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cycc_EquityOfferingTable_1" xlink:to="loc_dei_LegalEntityAxis_20" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_21"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_20" xlink:to="loc_dei_EntityDomain_21" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_21_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_20" xlink:to="loc_dei_EntityDomain_21_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_AspireCapitalFundLLCMember" xlink:label="loc_cycc_AspireCapitalFundLLCMember_22"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_21" xlink:to="loc_cycc_AspireCapitalFundLLCMember_22" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForCash" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesIssuedForCash_23"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesIssuedForCash_23" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForCash" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForCash_24"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForCash_24" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_CommonStockPurchaseAgreementShares" xlink:label="loc_cycc_CommonStockPurchaseAgreementShares_25"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_CommonStockPurchaseAgreementShares_25" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_CommonStockPurchaseAgreementTermPeriod" xlink:label="loc_cycc_CommonStockPurchaseAgreementTermPeriod_26"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_CommonStockPurchaseAgreementTermPeriod_26" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PurchaseObligation" xlink:label="loc_us-gaap_PurchaseObligation_27"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_PurchaseObligation_27" order="50" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForNoncashConsideration" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesIssuedForNoncashConsideration_28"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesIssuedForNoncashConsideration_28" order="60" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_CommonStockUnderwritingAgreementShares" xlink:label="loc_cycc_CommonStockUnderwritingAgreementShares_29"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_CommonStockUnderwritingAgreementShares_29" order="70" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_30"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_30" order="80" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityIssuancePerShareAmount" xlink:label="loc_us-gaap_EquityIssuancePerShareAmount_31"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_EquityIssuancePerShareAmount_31" order="90" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_32"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_32" order="100" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_NumberOfSharesIssuedDuringPeriodSubjectToUnderwritersOverAllotmentOption" xlink:label="loc_cycc_NumberOfSharesIssuedDuringPeriodSubjectToUnderwritersOverAllotmentOption_33"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_NumberOfSharesIssuedDuringPeriodSubjectToUnderwritersOverAllotmentOption_33" order="110" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_34"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_34" order="120" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForServices_35"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForServices_35" order="130" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ExpenseRelatedToStockPurchaseAgreement" xlink:label="loc_cycc_ExpenseRelatedToStockPurchaseAgreement_36"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_ExpenseRelatedToStockPurchaseAgreement_36" order="140" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquity_37"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquity_37" order="150" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityIssuancePerShareAmountNumberOfDaysUsedToCalculateAverageClosingPrice" xlink:label="loc_cycc_EquityIssuancePerShareAmountNumberOfDaysUsedToCalculateAverageClosingPrice_38"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_EquityIssuancePerShareAmountNumberOfDaysUsedToCalculateAverageClosingPrice_38" order="160" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_FinancingAgreementAmountToBePaidAsPercentageOfFutureLitigationSettlementReceived" xlink:label="loc_cycc_FinancingAgreementAmountToBePaidAsPercentageOfFutureLitigationSettlementReceived_39"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_FinancingAgreementAmountToBePaidAsPercentageOfFutureLitigationSettlementReceived_39" order="170" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityIssuanceLockUpPeriod" xlink:label="loc_cycc_EquityIssuanceLockUpPeriod_40"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_EquityIssuanceLockUpPeriod_40" order="180" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EconomicRightSettledForPayments" xlink:label="loc_cycc_EconomicRightSettledForPayments_41"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_EconomicRightSettledForPayments_41" order="190" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/Stockholdersequitydetails6">
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingLineItems" xlink:label="loc_cycc_EquityOfferingLineItems_0"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingTable" xlink:label="loc_cycc_EquityOfferingTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_EquityOfferingTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentsAxis" xlink:label="loc_cycc_EquityOfferingComponentsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cycc_EquityOfferingTable_1" xlink:to="loc_cycc_EquityOfferingComponentsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentDomain" xlink:label="loc_cycc_EquityOfferingComponentDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cycc_EquityOfferingComponentsAxis_2" xlink:to="loc_cycc_EquityOfferingComponentDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_EquityOfferingComponentDomain" xlink:label="loc_cycc_EquityOfferingComponentDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cycc_EquityOfferingComponentsAxis_2" xlink:to="loc_cycc_EquityOfferingComponentDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_July2009StockIssuanceMember" xlink:label="loc_cycc_July2009StockIssuanceMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_July2009StockIssuanceMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_January2010StockIssuanceOneMember" xlink:label="loc_cycc_January2010StockIssuanceOneMember_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_January2010StockIssuanceOneMember_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_January2010StockIssuanceTwoMember" xlink:label="loc_cycc_January2010StockIssuanceTwoMember_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_January2010StockIssuanceTwoMember_6" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_October2010StockIssuanceMember" xlink:label="loc_cycc_October2010StockIssuanceMember_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_October2010StockIssuanceMember_7" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_July2011StockIssuanceMember" xlink:label="loc_cycc_July2011StockIssuanceMember_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingComponentDomain_3" xlink:to="loc_cycc_July2011StockIssuanceMember_8" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ClassOfWarrantOrRightAbstract" xlink:label="loc_cycc_ClassOfWarrantOrRightAbstract_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_EquityOfferingLineItems_0" xlink:to="loc_cycc_ClassOfWarrantOrRightAbstract_9" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ClassOfWarrantOrRightAbstract_9" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_10" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ClassOfWarrantOrRightAbstract_9" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_11" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cycc_ClassOfWarrantOrRightAbstract_9" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_12" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/DiscontinuedOperationsDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ProductPromotionAndSaleOperationMember" xlink:label="loc_cycc_ProductPromotionAndSaleOperationMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3" xlink:to="loc_cycc_ProductPromotionAndSaleOperationMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestIncome" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestIncome_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_5" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestIncome_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_5" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_7" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationIncomeStatementDisclosuresAbstract_5" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_8" order="20" use="optional"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.cyclacel.com/role/DiscontinuedOperationsDetails2">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1" order="0" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3_Default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3_Default" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_ProductPromotionAndSaleOperationMember" xlink:label="loc_cycc_ProductPromotionAndSaleOperationMember_4"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3" xlink:to="loc_cycc_ProductPromotionAndSaleOperationMember_4" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_5"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_5" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_DisposalGroupIncludingDiscontinuedOperationShortTermPortionOfMinimumRoyaltyArrangementReceivableNet" xlink:label="loc_cycc_DisposalGroupIncludingDiscontinuedOperationShortTermPortionOfMinimumRoyaltyArrangementReceivableNet_6"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_5" xlink:to="loc_cycc_DisposalGroupIncludingDiscontinuedOperationShortTermPortionOfMinimumRoyaltyArrangementReceivableNet_6" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_DisposalGroupIncludingDiscontinuedOperationReturnsIndemnificationReceivableNet" xlink:label="loc_cycc_DisposalGroupIncludingDiscontinuedOperationReturnsIndemnificationReceivableNet_7"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_5" xlink:to="loc_cycc_DisposalGroupIncludingDiscontinuedOperationReturnsIndemnificationReceivableNet_7" order="10" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_8"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_5" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_8" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract_9"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract_9" order="20" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_DisposalGroupIncludingDiscontinuedOperationLongTermPortionOfMinimumRoyaltyArrangementReceivableNet" xlink:label="loc_cycc_DisposalGroupIncludingDiscontinuedOperationLongTermPortionOfMinimumRoyaltyArrangementReceivableNet_10"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationNoncurrentAbstract_9" xlink:to="loc_cycc_DisposalGroupIncludingDiscontinuedOperationLongTermPortionOfMinimumRoyaltyArrangementReceivableNet_10" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_11"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_11" order="30" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_12"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_12" order="40" use="optional"/>
<loc xlink:type="locator" xlink:href="cycc-20140630.xsd#cycc_DisposalGroupIncludingDiscontinuedOperationReturnsProvision" xlink:label="loc_cycc_DisposalGroupIncludingDiscontinuedOperationReturnsProvision_13"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_12" xlink:to="loc_cycc_DisposalGroupIncludingDiscontinuedOperationReturnsProvision_13" order="0" use="optional"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_14"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrentAbstract_12" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_14" order="10" use="optional"/>
</definitionLink>
</linkbase>


