TET1 and hepatocellular carcinoma: To further explore the relationship between 5-hmC level and SP cells in HCC, we conducted an Immunofluorescence assay (IF) in vitro and found that Huh7 SP cells have an apparent reduction of 5-hmC level than non-SP cells (Fig. 2A), which is related to TET2 repression rather than TET1 or TET3 deletion (Fig. 2B, C), indicating that TET2 deficiency-induced 5-hmC reduction is relevant to chemoresistance in HCC.