RB1 and urothelial carcinoma: Loss of cell cycle control is characteristic of carcinogenesis in urothelial carcinoma, as in many other cancers, due to the inactivation of cell cycle-regulating tumor suppressor genes (including TP53, RB, ATM), mutation of cell cycle progression regulators (CDKN1A, CDKN2A, CCND1, and CCNE1), or activating mutations of genes promoting cell cycle progression (including MDM2 and E2F3).