This protein is a member of the PDGF (platelet-derived growth factor)/VEGF (vascular endothelial growth factor) family. The VEGF family members regulate the formation of blood vessels and are involved in endothelial cell physiology. This member is a ligand for VEGFR-1 (vascular endothelial growth factor receptor 1) and NRP-1 (neuropilin-1). Studies in mice showed that this gene was co-expressed with nuclear-encoded mitochondrial genes and the encoded protein specifically controlled endothelial uptake of fatty acids. Alternatively spliced transcript variants encoding distinct isoforms have been identified.