CTNNB1 and adenoma: Of significant interest in terms of a likely key mechanisms through which Ctnnb1 gene dosage inhibits adenoma formation, the inability of the Apc-mutant colon epithelial cells to up-regulate and alter the crypt (high)-surface (low) gradient of EphB2/B3 expression appears to restrict high levels of EphB2/3 expression to the crypt base.