Basement-membrane protein 40, BM-40,Osteonectin, ON, Secreted protein acidic and rich in cysteine, Sparc

SPARC, also known as osteonectin and BM40, is a secreted matricellular glycoprotein that belongs to a group of functionally related glycoproteins that includes tenascins C and X, thrombospondins 1 and 2, and osteopontin. It is a major bone-related protein that is also present in nonmineralized tissues and in platelets and is matricellular molecule regulating interactions between cells and their surrounding extracellular matrix (ECM). This protein is produced by fibroblasts, capillary endothelial cells, platelets and macrophages, especially in areas of tissue morphogenesis and remodeling. It shows context-specific effects, but generally inhibits adhesion, spreading and proliferation, and promotes collagen matrix formation. It is abundantly expressed in bone, where it promotes osteoblast differentiation and inhibits adipogenesis.