AOM/DSS treatment of Myd88^−/− mice results in decreased proliferation and enhanced apoptosis of colonic epithelial cells and increased expression of mitogenic, angiogenic, and pro-tumorigenic genes. Cohorts of 10 WT and Myd88^−/− mice were injected i.v. with AOM on day 0 followed by 3 d of DSS administration in drinking water. Thereafter, colons were resected, fixed in formalin, and sections were stained with Ki67 or ApopTag antibodies. Photomicrographs of representative sections from the respective groups are shown at 400× magnification (A). The number of proliferating cells per crypt and the number of apoptotic cells was determined by counting 20 consecutive crypts/section (B and C). Gene expression profile in colon tissue after AOM/DSS treatment was analyzed by real-time RT-PCR. The gene expression was normalized to Gapdh levels, and the expression of each gene relative to untreated WT mice is depicted (D). The data shown in A–D correspond to a representative experiment out of two performed. Data represent means ± SE. *, P < 0.05; **, P < 0.01; ***, P < 0.001.