DNMT1 and esophageal squamous cell carcinoma: ChIP-PCRs in ESCC cell lines demonstrated that the p16 promoter regions (p16-1, p16-2, and p16-3) have less enrichments of DNMT1 and HDAC2 in ESCC cells after treatment with PAR4-AP for 2, 6, and 12 h, compared with controls (P < 0.05) (Figures 3(b)–3(e)).