Despite the fact that the percentage of CD133+ cells varies widely in established endometrial cancer cell lines, the level of mRNA encoding CD133 was elevated following treatment with the demethylating agent, 5-aza-2'-deoxycitidine (5-aza-dc), suggesting that methylation status may be important in the regulation of CD133 expression or epitope presentation. This evidence concerns the gene PROM1 and endometrial cancer.