S100A4 and osteosarcoma: Notably, both WiDr and PM1 cells responded with induction of STAT1 after incubation with 50 U ml−1 IFN-γ for 48 h (results not shown), suggesting that the difference in S100A4 response could not be explained by increased sensitivity to IFN-γ in the osteosarcoma cells in general.