Immunohistochemistry staining in human HCC cases confirmed that ENTPD2 was also overexpressed in protein level in human HCCs relative to their NT counterparts (Fig. 1g) and its staining followed a typical oxygen diffusion pattern (Supplementary Fig. 1b) as we reported previously24, suggesting that ENTPD2 is tightly regulated by hypoxia. This evidence concerns the gene ENTPD2 and hepatocellular carcinoma.