GPER1 and hepatocellular carcinoma: In HCC tissues, ESR1 mRNA level was positively correlated with ESRRB (r = 0.3441, P = 0.0006), PGRMC1 (r = 0.5124, P < 0.0001) and GPER (r = 0.2274, P = 0.0259) (Fig. 9).