Expression of exogenous Plk1 and p53 in lung carcinoma H1299 cells deficient in p53 greatly decreased the p53-mediated transcription of the p53-responsive p21, MDM2, and BAX promoters, whereas the kinase-deficient mutant Plk1 failed to reduce the transcriptional activity of p53 [90], suggesting that Plk1-mediated negative regulation of p53 might be a fundamental mechanism for the role of Plk1 in oncogenesis. This evidence concerns the gene TP53 and lung carcinoma.