MSH2 and colon adenoma: Immunostaining for MSH2 showed that all colonic adenomas tested from both ethanol-treated induced Aldh1b1−/− Msh2-LS and induced Aldh1b1flox/flox Msh2-LS mice had MSH2-negative dysplastic glands, surrounded by or admixed with MSH2-positive crypts showing normal, reactive or hyperproliferative changes (Fig. 2A,B,M; Fig. S5A,B,M).