ESR1 and hepatocellular carcinoma: In ER-positive MCF7 breast cancer cells, GREB1 expression was dramatically decreased by treatment with ICI.182.780 and also reduced by in response to CHIR99021 (Supplementary Fig. 1e), indicating that HepG2 and MCF7 cells regulate GREB1 expression in a different manner. Furthermore, CHIR99021 treatment did not induce GREB1 expression in HLE, SNU387, SNU449, and Huh7, human HCC cell lines in which GREB1 was little expressed (Supplementary Fig. 1f).