Description: Vascular endothelial growth factor (VEGF), also called vascular permeability factor (VPF), is produced by cultured vascular smooth muscle cells. From analysis of transcripts from these cells by PCR and cDNA cloning, 3 different forms of the VEGF coding region have been identified. These cDNAs had predicted products of 189, 165, and 121 amino acids. VEGF is a mitogen primarily for vascular endothelial cells. It is structurally related to platelet-derived growth factor. VEGF, a homodimeric glycoprotein of relative molecular mass 45,000, is the only mitogen that specifically acts on endothelial cells. The VEGF receptor, Flk1, is exclusively expressed in endothelial cells. VEGF may be a major regulator of tumor angiogenesis in vivo.