Vascular endothelial growth factor (VEGF) plays a central role in tumor angiogenesis. It stimulates endothelial cell proliferation and vessel hyperpermeability, promotes cell migration, and inhibits apoptosis. All these actions of VEGF are mediated by receptor tyrosine kinase, vascular endothelial growth factor receptor (VEGFR). Selective targeting VEGFR signal transduction pathway may be proved to be useful in developing tumor angiogensis inhibitors.