Higher TET1, 2, 3 and 5-hmC expressions were detected in low metastatic HCC cells lines (SMMC-7721 and HepG2), whereas lower TET1, 2, 3 and 5-hmC expressions were detected in highly metastatic HCC cell lines HCCLM3 and MHCC97H. Here, TET1 is linked to hepatocellular carcinoma.