<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Any substance that inhibits amidophosphoribosyltransferase, an enzyme that catalyzes the commiting step on de novo purine synthesis. Inhibition of amidophosphoribosyltransferase inhibits DNA synthesis and results in cell cycle arrest.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>