According to a previous report, promoter methylation is closely related to the inactivation of KLF4.6 In addition, ten‐eleven translocation (TET) enzymes mainly oxidize 5‐methylcytosine (5‐mC) into 5‐hydroxymethyl cytosine (5‐hmC) and participate in cytosine methylation and cell differentiation.15, 16, 17 However, it has been reported that TET1 decreased prominently in CagA‐infected GC tissues compared with that in para‐carcinoma tissues.18 Hence, we sought to explore how KLF4 is inactivated in GC and aimed to analyze the relationships among CagA, KLF4, and TET1. The gene discussed is TET1; the disease is carcinoma.