TP53 and lymphoma: Since all 3 Fbxw7 alleles were segregating within this population, we tested the possibility of association between lymphoma development and the presence of the candidate susceptibility SNP in Fbxw7. While there was no detectable influence of the Asp61Asn polymorphism in Fbxw7 on lymphoma development in p53−/− mice (Fig. 2B), a significant effect was detected at the same SNP in radiation-induced lymphomas from p53+/− mice (Fig. 2A).