PROM1 and hepatocellular carcinoma: Although CD133 protein levels in HCC tissues without intrahepatic metastasis were not correlated with GPR87 expression (R = 0.120, P>0.05) (Table S4, S5), the CD133 protein levels in HCC tissues with intrahepatic metastasis positively correlated with GPR87 expression (R = 0.267, P<0.05) (Figure 4E, F; Table 1), suggesting that CD133 might be up-regulated by the expression of GPR87 in metastatic HCC.