Alpha-2-HS-glycoprotein (AHSG) is also known as Alpha-2-Z-globulin, Ba-alpha-2-glycoprotein, Fetuin-A (FETUA), is a glycoprotein that is composed of two subunits, the A and B chains, belongs to the cystatin family of proteases inhibitors and the fetuin class of plasma binding proteins. AHSG / Fetuin A is highly expressed in embryonic cells and adult hepatocytes, and is expressed to a lesser extent in monocytes/macrophages. Fetuins are carrier proteins like albumin. Fetuin-A / AHSG forms soluble complexes with calcium and phosphate and thus is a carrier of otherwise insoluble calcium phosphate. Thus AHSG / Fetuin A is a potent inhibitor of pathological calcification. Fetuin A / FETUA promotes phagocytosis of apoptotic cells and plays a role in bone development, calcium homeostasis and insulin sensitivity. Mice deficient in Fetuin-A show systemic calcification of soft tissues.