Among 28 lung tumors, eight tumors (29%) contained K-ras mutation in codon 61, and its frequency was similar between transgenics (27%) and non-transgenics (29%) and between the 4–12 months transgenic cohort (33%) and the 13–24 months transgenic cohort (27%), suggesting its lack of association with age or collaboration with P53 mutations (4–15 months vs. 16–24 months: Fisher's exact p = 0.936). The gene discussed is TP53; the disease is lung neoplasm.