MSH2 and adenoma: Expression of the β-catenin protein (CTNNB1) was investigated by IHC in colonic tumours from ethanol-treated induced Aldh1b1−/− Msh2-LS mice, which showed a heterogeneous pattern with variable numbers of adenoma cells with moderately to strongly positive β-catenin nuclear immunostaining owing to accumulation and translocation of β-catenin into tumour nuclei (Fig. 2E,F).