In the next step, we treated with exogenous FGF1 two osteosarcoma lines expressing FGFR1 (G292 expressing endogenous FGFR1 [52] and U2OS stably transfected with FGFR1 (U2OS_R1)), but differing in p53 status. Here, FGF1 is linked to osteosarcoma.