Mouse vascular endothelial growth factor 164 (VEGF 164) is produced as a homodimer. It binds to the FLT1/VEGFR1 and KDR/VEGFR2 receptors, heparan sulfate and heparin. It is a specific mitogen for vascular endothelial cells and a strong angiogenic factor in vivo. In addition to its action as a mitogen it is a potent vascular permeability factor (VPF) in vivo and is also a chemoattractant for monocytes and endothelial cells. It induces endothelial cell proliferation, promotes cell migration, inhibits apoptosis and induces permeabilization of blood vessels. 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.