Vascular endothelial growth factor (VEGF) activates endothelial cells, in part, by interacting with the kinase insert domain-containing receptor (KDR) receptor tyrosine kinase. Although progress has been made in the identification of cell-signaling proteins that participate in the VEGF-induced response, questions remain concerning the molecular interactions that allow coupling of receptor activation with an increased cellular response. Evidence is provided in this manuscript that indicates a role for the fibroblast growth factor receptor substrate 2 (FRS2) in VEGF-induced signal transduction. VEGF treatment of human umbilical vein endothelial cells (HUVECs) and KDR-transfected porcine aortic endothelial cells leads to the rapid tyrosine phosphorylation of FRS2. FRS2 is associated constitutively with KDR, and VEGF treatment has no effect on this interaction. VEGF treatment of KDR-expressing cells leads to the recruitment of Nck, p21-activated kinase, Crk, Grb2, and protein kinase C l to FRS2. The ability of FRS2 to recruit cell-signaling proteins to the cell is significant because it provides a mechanism for enhancing the repertoire of VEGF-induced signaling pathways.