– Vitronectin, also known as VTN, is a large glycoprotein found in blood and the extracellular matrix (ECM). Vitronectin is a plasma glycoprotein implicated as a regulator of diverse physiological process, including blood coagulation, fibrinolysis, pericellular proteolysis, complement dependent immune responses, and cell attachment and spreading. Blocking of Hic(a member of the pneumococcal surface protein C (PspC) family) by specific antiserum or genetic deletion significantly reduced pneumococcal binding to soluble and immobilised vitronectin and to Factor H, respectively. In addition, Vitronectin interact with glycosaminoglycans and proteoglycans. Is recognized by certain members of the integrin family and serves as a cell-to-substrate adhesion molecule. Inhibitor of the membrane-damaging effect of the terminal cytolytic complement pathway.