It was found that while Trp53 inactivation in the mouse prostate failed to produce neoplasia, and Pten inactivation produced non-lethal invasive prostate cancer after a long latency, the combined inactivation of Trp53 and Pten in the prostate elicited invasive prostate cancer in mice as young as two weeks of age. This evidence concerns the gene TP53 and neoplasm.