Despite the previous negative data using Atm-heterozygous mice, we reasoned that the role of Atm in K-RasV12-driven lung tumorigenesis could perhaps be revealed in mice completely deficient in Atm. For this, we sacrificed Atm-null and Atm-wt mice carrying the activated K-RasV12 allele at 5 months of age (4 months post-activation with OHT), when most Atm-null mice had not developed yet frank lymphomas but lung tumors were already present. Here, ATM is linked to lymphoma.