To directly assess whether loss of Pkd1 affects the incidence or presentation of colorectal cancer, we used an inducible CRC mouse model in which biallelic loss of a floxed allele of Apc (Apcfl/fl) is induced by CreERT2 (in which tamoxifen induces Cre-lox dependent targeted inactivation), with CreERT under the control of the Cdx2 promoter, and expressed specifically in the epithelium of the distal ileum, cecum, and colon (Cdx2ERT-Apcfl/fl mice; designated Apc−/− hereafter). The gene discussed is PKD1; the disease is colorectal carcinoma.