FN1 and prostate cancer: Similarly, the small-molecule peptide antagonist ATN-161 (Ac-PHSCN-NH2), derived from the FN synergy site, competitively inhibits α5β1–FN binding and, in preclinical models of breast and prostate cancer bone metastasis, suppresses MMP-1–mediated tumor invasion, angiogenesis, and osteolysis (Cianfrocca et al., 2006; Khalili et al., 2006; Doñate et al., 2008).