VEGF-121 plays a role in angiogenesis, and induces endothelial cell proliferation and cell migration. It also functions as a part of osteoclastogenesis. In contrast to other factors mitogenic for endothelial cells such as FGF-1, FGF-2 and PDGF, VEGF is synthesized as a precursor containing a typical hydrophobic secretory signal sequence of 26 amino acids. Glycosylation is not required for efficient secretion of VEGF. rHu VEGF-121 produced in E. coli is a double, non-glycosylated, polypeptide chain that contains 122 amino acids and has a molecular mass of 28.42 kDa.