HELLS and intrahepatic cholangiocarcinoma: ICC (Immunocytochemistry) and ELISA (Enzyme-Linked Immunosorbent Assay) revealed that HELLS knockdown decreased 5-hydroxymethylcytosine (5hmC) and increased 5-methylcytosine (5mC) levels in four cancer cell lines (Fig. 6A and Supplementary Fig. S8A).