Alpha-2-HS-glycoprotein (AHSG) is a glycoprotein that is composed of two subunits, the A and B chains, belongs to the Cystatin family of proteases inhibitors. It is highly expressed in embryonic cells and adult hepatocytes, and is expressed to a lesser extent in monocytes/macrophages. AHSG is an important circulating inhibitor of calcification in vivo, and is downregulated during the acute-phase response. It is involved in several functions, such as endocytosis, brain development and the formation of bone tissue. In addition, AHSG may influence the resolution of inflammation by modulating the phagocytosis of apoptotic cells by macrophages. ASHG blocks TGF-beta-dependent signaling in osteoblastic cells.