MSH2 and colon adenoma: In the ethanol-treated induced Aldh1b1flox/flox Msh2-LS mice, 5/12 (41.6%) demonstrated colonic epithelial hyperproliferation with colonic adenoma formation and, in one case, invasive adenocarcinoma, all within an average of 4.5 months (Fig. 1A,C; Fig. S1A-D).