Platelet-derived growth factor (PDGF) was discovered as a major mitogenic factor present in serum but absent from plasma. In vitro, PDGF-BB stimulated MAP kinase activity and cell motility of isolated lymphatic endothelial cells. In vivo, PDGF-BB potently induced growth of lymphatic vessels. Expression of PDGF-BB in murine fibrosarcoma cells induced tumor lymphangiogenesis, leading to enhanced metastasis in lymph nodes. The PDGF signaling system contributes to and vascular remodeling. Growth factors such as PDGF exert potent effects on wound healing including the regeneration of tooth-supporting structures.