In order to expand our knowledge on the methylation status of these CGIs in tumors, we compared the methylation levels between the six selected CGIs in seven additional HCC tumors (see representative pictures of their morphology and histology in Supplementary Figure 1B,C) and their matched non-tumor liver tissues of 16-month-old Mdr2-KO mice using MSRE-PCR (Supplementary Table 4; Supplementary Figure 8). Here, ABCB4 is linked to hepatocellular carcinoma.