Mouse Vascular endothelial growth factor (VEGF or VEGF-A), is a potent mediator of both angiogenesis and vasculogenesis in the fetus and adult. It is a member of the PDGF/VEGF growth factor family that is characterized by a cystine knot structure formed by eight conserved cysteine residues. Alternately spliced isoforms of 120, 164 and 188 aa found in mouse. VEGF binds the type I transmembrane receptor tyrosine kinases VEGF R1 (also called Flt-1) and VEGF R2 (Flk-/KDR) on endothelial cells.Although affinity is highest for binding to VEGF R1, VEGF R2 appears to be the primary mediator of VEGF angiogenic activity. VEGF is required during embryogenesis to regulate the proliferation, migration, and survival of endothelial cells.It 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.