To determine the number of traceable cells per tumour, Ctnnb1 was first recombined in the intestinal epithelium of AhCreErt;Ctnnb1lox(ex3);RDrePr;RtdTomrsr animals by activating AhCreErt with β-naphthoflavone and tamoxifen. The gene discussed is CTNNB1; the disease is neoplasm.