VEGF, also known as vascular endothelial growth factor, vasculotropin, and vascular permeability factor, is a widely expressed mitogen for vascular endothelial cells that has been shown to promote angiogenesis and increase permeability of capillary blood vessels. VEGF is a member of the platelet-derived growth factor (PDGF) family and is produced as a homodimeric protein with approximate molecular weights of 34-46 kD. The variance in molecular weight is a result of alternative splicing events that encode monomeric proteins having 121, 165, 189 or 206 amino acids. VEGF121 and VEGF165 are secreted proteins whereas VEGF189 and VEGF206 are strongly cell-associated. VEGF binds to VEGF-R1 (also known as Flt-1) and VEGF-R2 (also known as KDR). Inhibition of VEGF biding to VEGF-Rs has been the focus of a number of tumor therapeutic strategies. The Poly6275 antibody recognizes the N-terminal region of human VEGF has been shown to be useful for Western blotting of both reduced and non-reduced VEGF.