This strain is a mouse model lacking Trp53, which is a gene homologous to human TP53. Homozygous Trp53-KO male mice develop normally but are prone to spontaneous tumors. Homozygous Trp53-KO mice developed tumors, mainly lymphomas, and sarcomas, at three to six months of age, and heterozygous mice developed tumors at about 10 months of age. Homozygous males are viable and fertile, but homozygous females have reduced survival at weaning.