VEGFR-1 (vascular endothelial growth factor receptor 1) is a 180- kDa membrane receptor tyrosine kinase that is the receptor for vascular endothelial growth factor (VEGF), VEGFB and PGF. VEGF is a key regulator of physiological angiogenesis during embryogenesis, skeletal growth and reproductive functions. VEGF has also been implicated in pathological angiogenesis associated with tumors, intraocular neovascular disorders and other conditions (1). VEGFR-1 has seven extracellular Ig-like domains, the second domain from the N-terminus is necessary and sufficient for high affinity VEGF binding (2). The biological effects of VEGF are mediated by VEGFR-1 and VEGFR-2 (1), and two major tyrosine phosphorylation sites at Tyr 1213 and Tyr 1242 and two minor tyrosine phosphorylation sites at Tyr 1327 and Tyr 1333 exist in VEGFR-1 (3).