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. Required for normal proliferation and recruitment of pericytes and vascular smooth muscle cells in the central nervous system, skin, lung, heart and placenta. Required for normal blood vessel development, and for normal development of kidney glomeruli. Plays an important role in wound healing. Signaling is modulated by the formation of heterodimers with PDGFA (By similarity). Antiparallel homodimer; disulfide-linked. Antiparallel heterodimer with PDGFA; disulfide-linked. The PDGFB homodimer interacts with PDGFRA and PDGFRB homodimers, and with heterodimers formed by PDGFRA and PDGFRB. The heterodimer composed of PDGFA and PDGFB interacts with PDGFRB homodimers, and with heterodimers formed by PDGFRA and PDGFRB. Interacts with XLKD1 (By similarity). Interacts with LRP1 (By similarity). Interacts with SORL1 (via the N-terminal ectodomain) (By similarity). Released by platelets upon wounding. Expressed in a distinct subpopulation of smooth muscle cells in injured arteries. Belongs to the PDGF/VEGF growth factor family.