<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Any substance that inhibits inosine monophosphate dehydrogenase, an enzyme that catalyzes the conversion of inosine monophosphate to xanthosine monophosphate, the rate-limiting step in the de novo biosynthesis of guanine nucleotides. Inhibition of inosine monophosphate dehydrogenase can lead to inhibition of cell proliferation.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>