TP53 and neoplasm: To develop a deeper understanding of the effects of radiation on tumour DNA integrity, we use mouse strains with partial germline deficiency in Trp53 function, i.e., mice hemizygous for Trp53 (Trp53(+/−)), or homozygous for the Delta P Trp53 allele (Trp53(DP/DP)); hereafter Trp53ΔP).