TP53 and neoplasm: To decipher the role of the V(D)J recombinase in lymphomagenesis, we bred Rag2−/− mice (Shinkai et al., 1992) with p53−/− mice (Jacks et al., 1994) and followed tumor appearance in p53−/− and Rag2−/−p53−/− mice (Figures S1 and S2).