To clarify the potential roles of the various DNMTs in mediating miR-378a-3p promoter methylation in HCC, we knocked down DNMT1, DNA methyltransferase 3 alpha (DNMT3A), and DNA methyltransferase 3 beta (DNMT3B) in HCC cells using specific small interfering RNAs (siRNAs) (Fig. 6C, D). Here, DNMT3A is linked to hepatocellular carcinoma.