To confirm the regulation of TFF1 expression by its promoter methylation, we treated the ESCC-derived cell lines TE-1 and TE-13 with 2.5 μM decitabine (5-aza-2′-deoxycytidine, DNA methyltransferase inhibitor) for 72 h, resulting in more than 50% cell viability (Fig. 3a). Here, TFF1 is linked to esophageal squamous cell carcinoma.