TP53 and cancer: On a C57BL/6 background, around 60–75% of female Trp53−/− mice die during embryogenesis due to defects in neural tube closure (Delbridge et al, 2019; Jacks et al, 1994), and 100% of Trp53−/− mice (or mice with hypomorphic alleles of Trp53) develop cancer, mostly thymic T cell lymphoma, within 300 days (Donehower et al, 1992; Jacks et al, 1994; Valente et al, 2013).