Rabbit Anti-Human OPN-R monoclonal antibody for FC, ICC, IF, WB. Osteopontin is a 34kDa extracellular matrix protein with a cell binding domain. It was originally identified as a major component of the non-collagenous organic bone matrix, however, it has subsequently been demonstrated in a wide range of normal adult tissue and body fluids. It is a multifunctional protein involved in bone mineralization, cell adhesion, cell migration, chronic inflammatory disease and transformation. Proteolytic cleavage by thrombin and matrix metalloproteinases close to the integrin-binding Arg-Gly-Asp sequence modulates the function of OPN and its integrin binding properties. Thrombin-cleaved fragments of Osteopontin are overexpressed in malignant glial tumors and provide a molecular niche with survival advantage and provide a novel substrate for plasmin and cathepsin D.