Growth factor for endothelial cells. VEGF-B167 binds heparin and neuropilin-1 whereas the binding to neuropilin-1 of VEGF-B186 is regulated by proteolysis. VEGF-B seems to be required for normal heart function in adult but is not required for proper development of the cardiovascular system either during development or for angiogenesis in adults. Homodimer; disulfide-linked. Can also form heterodimer with VEGF. Secreted but remains associated to cells or to the extracellular matrix unless released by heparin. Additional isoforms seem to exist. Abundantly expressed in heart, brain, kidney and skeletal muscle. VEGF-B186 is O-glycosylated. Belongs to the PDGF/VEGF growth factor family.