Vitronectin (also known as serum spreading factor, S protein of complement or epibolin) is one of the major multifunctional cell adhesive glycoproteins in mammalian plasma and serum. It is a monomeric acidic glycoprotein detected as a mixture of 75 kD and 65 kD polypeptides. Vitronectin binds to heparin, collagen, streptococci and variety of cultured cells. It also acts as an inhibitor of the complement cascade by binding to the C5b9 complex. Vitronectin promotes cell adhesion and spreading