<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A 16 kD N-terminal fragment of prolactin formed endogenously by cleavage of intact prolactin. Possessing anti-angiogenic properties, prolactin 16-kD fragment inhibits the pro-angiogenic effects of basal fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) on endothelial cell proliferation, migration, and capillary organization. This agent also induces caspase-mediated endothelial cell apoptosis and upregulates the expression of plasminogen activator inhibitor-1 (PAI-1); PAI-1 inhibits the activity of urokinase, an enzyme essential to angiogenesis. (NCI04)</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>