<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Any substance that inhibits phosphatidylinositol 3-kinase (phosphatidylinositide 3-kinase), an enzyme that catalyzes the phosphorylation of the 3 position hydroxyl group of the inositol ring of phosphatidylinositol and functions as an intracellular signal transducer in cell growth, proliferation, differentiation, motility, survival and intracellular trafficking. Inhibition of phosphatidylinositol 3-kinase produces antiproliferative and antiangiogenic effects.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>