GRGDS is the cell adhesion sequence of osteopontin that recognizes the avb3 integrin. Osteopontin is overexpressed in experimental models of malignancy. Although the native form of OPN is active in cell attachment assays, it has been observed that thrombin cleavage of OPN causes substantial enhancement of it's attachment properties. This cleavage occurs within residues of the GRGDS sequence raising the possibility of thrombin-cleavage further activating OPN by allowing greater accessibility of the GRGDS domain to cell surface receptors. GRGDS synthetic peptide also mimics the cellular binding site of many adhesive proteins in the extracellular matrix and causes rounding and detachment of spread cells. It induces dissociation of alpha-actinin and vinculin from the sites of focal contacts.