Neoplastic cells from tumors that developed in aged mice (‘aged cancer cells’) had a striking enrichment for several signatures of lung epithelial23,38 and global aging42 when compared to neoplastic cells from tumors that developed in young mice (‘young cancer cells’), suggesting that oncogenic KRAS-driven lung tumorigenesis does not revert these fundamental changes (Fig. 4e). The gene discussed is KRAS; the disease is cancer.