RB1 and urinary bladder carcinoma: While cell cycle regulators in bladder cancers may be more regularly mutated than in some other cancer types [50], most alterations concern TP53, RB1, and CDKN2A, which are also frequently mutated in other cancer types—e.g., lung, colorectal, and brain cancers—and are known to contribute to deficient G1 checkpoint control in UC [51].