FGFR1 and neoplasm: FGF-5 is a ligand for FGFR1 and FGFR2, and to determine whether inhibition of FGFR1 activation alone was responsible for CCL5 reporter activity induced in mammary fibroblasts by tumor-derived factors, we pre-treated mammary fibroblasts with the selective FGFR1 inhibitor SSR128129E prior to stimulation with breast cancer cell-conditioned media (Figure 6D).