RNF135 and hepatocellular carcinoma: However, the expression of the six genes (EFNB2, MTHFD2, TSC22D1, CELF6, SH3YL1, and RNF135) which exhibited DNA hypermethylation exclusively in HCC and not in other tumor types, was markedly low in liver tissue compared to other extrahepatic healthy tissues, suggesting a specific transcriptional repression in the liver.