Growth factor active in angiogenesis, vasculogenesis and endothelial cell growth. Induces endothelial cell proliferation, promotes cell migration, inhibits apoptosis and induces permeabilization of blood vessels. Binds to the FLT1/VEGFR1 and KDR/VEGFR2 receptors, heparan sulfate and heparin. May play a role in increasing vascular permeability during lactation, when increased transport of molecules from the blood is required for efficient milk protein synthesis (By similarity). (www.uniprot.org) Produced in E.coli as a homodimer, non-glycosylated, polypeptide chain containing 121 amino acids. Recombinant mouse VEGF-121 is a truncated version of murine VEGF-165.