To assess whether Fbxw7 plays a role in lung cancer development, we first carried out a genetic analysis of the Fbxw7 locus in our two previous mouse backcross studies: the first one was between SPRET/EiJ and FVB/NKras2LA2 mice where lung tumor development was initiated by knock‐in of mutant K‐ras (G12D), and the second was between SPRET/EiJ and FVB/N mice where lung tumor development was induced by a single treatment of urethane (To et al., 2006). The gene discussed is KRAS; the disease is lung cancer.