TP53 and colonic neoplasm: Here we report a complex mouse model of colon cancer which has been established utilizing this chimera approach, in which genetically modified ES-cells (p53-flox, p53-loxSTOPlox-R172H, GAPDH-loxSTOPlox-rtTA, and Villin-Cre) were engineered to express activated inducible β -Catenin (ΔN131) and mutated endogenous p53 (R172H) in the mouse gastrointestinal epithelium.