CDKN1A is known as one of the downstream genes of TP53. In this study, EBC2 lung SCC cells, TE1 and TE4 esophageal SCC cells harbor mutant TP53. TP53 expression was not altered after Ad-ATF/SOX2 infection in lung and esophageal squamous SCC cells, suggesting that ATF/SOX2 induces CDKN1A in TP53 independent manner (Figure 4) [15]. Here, CDKN1A is linked to infection.