Lung tumorigenesis induced by endogenous oncogenic K-Ras alleles faithfully recapitulates human lung adenocarcinoma [34], and presents two characteristics of relevance for this study, namely, tumorigenesis is suppressed by p53 [35], [36] and it is accompanied by a readily detectable senescence response at the pre-malignant tumor stages [37]. This evidence concerns the gene KRAS and neoplasm.