Growth factor that plays an essential role in the regulation of embryonic development, cell proliferation, cell migration, survival and chemotaxis. Potent mitogen for cells of mesenchymal origin. Plays an important role in wound healing. Induces macrophage recruitment, increased interstitial pressure, and blood vessel maturation during angiogenesis (By similarity). May play an important role in control of lens epithelial cell proliferation. Can initiate events that lead to a mesangial proliferative glomerulonephritis, including influx of monocytes and macrophages and production of extracellular matrix. Homodimer; disulfide-linked. Interacts with PDGFRB homodimers, and with heterodimers formed by PDGFRA and PDGFRB (By similarity). Released by platelets upon wounding. Widely expressed. Expressed at high levels in the kidney, adrenal glands, eye and CNS. In the kidney the localization is confined to arterial and arteriolar vascular smooth muscle cells and is also detected at low levels in the glomeruli In the eye in the anterior segment it is localized to the iris and ciliary body. In the retina localizes intensely to the outer plexiform layer, which contains photoreceptor axons and the synaptic layer between photoreceptors and second order neurons. In the spinal cord, prominently expressed in the motorneurons. Not detected in the spinal cord at E21. Expressed weakly at postnatal day 1 (P1) and a strong expression seen at P21 and this continues into adulthood. Activated by proteolytic cleavage. Proteolytic removal of the N-terminal CUB domain releasing the core domain is necessary for unmasking the receptor-binding epitopes of the core domain. Cleavage after Arg-247 or Arg-249 by urokinase plasminogen activator gives rise to the active form (By similarity). Belongs to the PDGF/VEGF growth factor family.