Impact of deletion of 1 allele of Mcl-1 selectively in T-lymphoid cells on thymic lymphoma development in p53^−/− mice. (A) Tumor-free survival of p53^−/−;Lck-Cre;Mcl-1^fl/+ mice (n = 44) in comparison with control mice (p53^−/−;Lck-Cre; n = 26; log-rank Mantel-Cox test, P = .1216). (B) Flow cytometric analysis of Mcl-1^fl recombination in 2 independent primary thymic lymphoma samples (TCRβ⁺CD4⁺CD8⁺) from p53^−/−;Lck-Cre;Mcl-1^fl/+ mice compared with a p53^−/−;Lck-Cre thymic lymphoma (negative control) by immunofluorescent staining for the human CD4 reporter. (C) Incidence in % of thymic lymphoma, splenomegaly, sarcoma, or other pathologies in the cohorts of p53^−/−;Lck-Cre (n = 26) and p53^−/−;Lck-Cre;Mcl-1^fl/+ mice (n = 44). (D) Analysis of the proteins indicated by western blotting of primary thymic lymphoma samples from mice of the indicated genotypes (representative of 6-10 samples each). Probing for HSP70 was used as a loading control. The numbers below western blots indicate the tumor samples also tested in B.