CTNNB1 and adenoma: immunohistochemical (IHC) analysis of pre-malignant colon tissue, polyps, and adenomas from Apc−/−Pkd1−/− versus Apc−/− mice confirmed elevated CTNNB1 expression and active (S675-phosphorylated) CTNNB1 associated with the Apc−/−Pkd1−/− genotype, as well as in Apc−/−Pkd1−/− organoids (Fig. 3D, E, Supp Fig. S3A, B).