Numerous studies have suggested that epigenetic modifications have an important role in the etiology of human diseases.40, 41 Abnormal hypermethylation of CpG islands of tumor-suppressor genes and their transcriptional silencing are associated with malignant transformation in cancer.42 DNMTs are ubiquitously expressed in normal human tissues and are overexpressed in many types of cancer.17, 18, 43 In our study, IHC analysis indicated that DNMT1 expression was significantly higher in bladder cancer tissues than in adjacent non-tumor tissues (P<0.001). The gene discussed is DNMT1; the disease is cancer.