In conclusions, we showed that increase of p53 levels by Ad-delE1B infection did not contribute to the Ad-mediated cytotoxicity, but further enhanced p53 expression with MDM2 inhibitors was associated with activation of the ATM-Chk2 pathway and augmented the cytotoxicity through upregulated NFI expression (summarized in Fig. 6E). This evidence concerns the gene MDM2 and infection.