BMI1 and Barrett esophagus: The aims of this study are (1) to investigate the association of high Bmi-1 expression with the oncogenic progression of esophageal adenocarcinoma from squamous mucosa, columnar cell metaplasia, Barrett’s esophagus, low- and high-grade dysplasia to adenocarcinoma, and (2) to determine the relationship of high Bmi-1 expression with clinicopathologic characteristics including gender, age, differentiation, and tumor stage in both esophageal adenocarcinoma and squamous cell carcinoma.