TP53 and cancer: Kadosh and colleagues first examined the cancer phenotypes in the proximal (duodenum and jejunum) and distal (ileum and colon) gastrointestinal tract of CKIa-deleted mice carrying wild-type p53 (CKIaΔgut), mutant p53 (CKIaΔgutp53R172H), or no p53 (CKIaΔgutp53Δgut).