TP53 and squamous cell lung carcinoma: These autoregulatory properties are altered when p53 is mutated; thus transcription-defective p53 mutants cause an accumulation of VRK1 because its degradation mechanism can not be induced [12], an observation that has been confirmed in human lung squamous cell carcinomas containing mutations in p53, which have very high levels of endogenous VRK1 [13].