RB1 and urinary bladder cancer: Early stage bladder cancer (pTa or pT1) is commonly linked to activating mutations of the FGFR3, HRAS or PI3K genes21, 22, 23, while advanced stage bladder cancer (≥pT2) is linked to mutations in the tumour suppressor genes TP53, RB, and PTEN, which can act as a negative regulators of the PI3K/Akt signaling pathway24, 25.