Western blotting analysis showed that Bmi-1 protein was highly expressed in four esophageal cancer cell lines (108CA, Kyse 140, Eca-109 and TE-1) and HPV E6/E7 induced immortalized cell line NE-3, whereas it was weakly detected in normal esophageal tissue (Fig. 1A). This evidence concerns the gene BMI1 and esophageal cancer.