TP53 and urothelial carcinoma: On the other hand, the tumor suppressor gene p53, the most frequently mutated tumor suppressor in human cancer, including urothelial carcinoma [45,46], also directly upregulates miR-34a [47,48,49], thereby explaining the fact that p53 signaling can control miR-34a expression, in UC samples, without miR-34a promoter methylation.