FGF19 and hepatocellular carcinoma: Histological analysis of mice ectopically expressing FGF19 revealed that glutamine synthetase-positive HCC tumours developed exclusively in Stat3f/f mice, but were not observed in Stat3ΔHep mice (Fig. 1d,g, and Supplementary Fig. 1b), suggesting that Stat3 deficiency in hepatocytes prevents HCC initiation and progression in response to FGF19.