Besides, downexpression of PTPRO in epithelial cells attributes to promoter methylation in multiple types of cancers, including hepatocellular carcinomas (HCC) (31), breast cancer (28, 32), lung cancer (27) and esophageal cancer (29), suggesting that PTPRO may be a candidate target for tumor epigenetic therapy. The gene discussed is PTPRO; the disease is breast carcinoma.