TP53 and neoplasm: By contrast, no Lck‐Cre;Ptpn2fl/fl;p53+/− mice (0/22) developed any overt tumours, splenomegaly or abnormal lymphocytic populations as assessed by gross morphology or flow cytometry and lymphoid organ tissue architecture was normal (Fig 1A and B, Appendix Fig S1, Appendix Table EV1).