However, the causal relationship between these mutations and bladder cancer development has not been well studied in genetic mouse models of bladder cancer due to the lack of suitable transgenic mice that can be used to inactivate these tumor suppressors in the adult, since Pten and Rb are required for embryonic development, and Pten/Rb deficient mice are not born [3], [4]. The gene discussed is RB1; the disease is urinary bladder carcinoma.