Ad5WS1 caused more severe cytolytic effect and replicated more efficiently in J82 and TCC-SUP bladder cancer cells carrying mutant p53compared with TSGH-8301 and BFTC-905 bladder cancer cells retaining wild-type p53. Introduction of dominant negative p53into BFTC-905 cells rendered them more susceptible to Ad5WS1-induced cytolysis. The gene discussed is TP53; the disease is urinary bladder cancer.