An antiphosphotyrosine antibody was used to identify proteins that are phosphorylated in Rous sarcoma virus-transformed chick embryo fibroblasts, and a 76-kD protein was obtained that localizes to focal adhesions at the ends of actin-containing stress fibers in nontransformed cells (Ref.1). This protein was purified from chicken gizzard smooth muscle, and was named Pxn (Paxillin) ('paxillus' means 'small stake' or 'peg' in Latin) as a protein tethered to the membrane at focal adhesions