DNMT1 expression in different cell lines and tissues. A: real-time RT-PCR showed that DNMT1 mRNA levels were significantly higher in esophageal adenocarcinoma (EA) cell lines FLO and OE33 than normal esophageal squamous epithelial cell line HET-1A or Barrett's cell lines BAR-T or CP-A (n = 3–10). DNMT1 mRNA levels were higher in BAR-T and CP-A cells than those in HET-1A cells, but the increase did not reach the statistical significance. B: DNMT1 mRNA levels were significantly increased in EA tissues, when compared with normal esophageal mucosa or Barrett's mucosa (n = 3–12). DNMT1 mRNA levels were higher in Barrett's mucosa than those in normal esophageal mucosa, but the increase did not reach the statistical significance. These data suggest that DNMT1 might be important in development of EA. ANOVA: *P < 0.01, #P < 0.02, compared with HET-1A cells, BAR-T cells, or CP-A cells; **P < 0.01, compared with normal esophageal mucosa (NESO) or Barrett's mucosa (BE).