G-R-G-D-N-P is a superior inhibitor of cell attachment to fibronectin and a weak inhibitor of cell attacment to vitronectin. It also inhibits binding of fibrinogen, fibronectin, vitronectin and von Willebrand factor to platelets and resists to carboxypeptidases. G-R-G-D-N-P induces apoptosis in various cell types and cell lines at 1mM by a mechanism involving cellular uptake and possible direct stimulation of procaspase-3 autoprocessing. It contains the motif RGD (Arg-Gly-Asp) which is found in many integrin ligands. G-R-G-D-N-P inhibits cell adhesion to fibronectin 80-90% at 1 mM.