A method of promoting cell attachment to a substrate, comprising the steps of:immobilizing on the substrate a composition of matter comprising a polypeptide X-Arg-Gly-Asp-R-Y wherein X is H or at least one amino acid and Y is OH or at least one amino acid, and R is an amino acid selected from Ser, Cys, Thr or other amino acid such that said peptide has cell attachment promoting activity, said poly