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Three separate groups of mice were used as controls: one group of mice was maintained with regular water (n = 16 WT; n = 10 Tg), a second group of mice was injected with AOM and given water for the remainder of the experiment (n = 9 WT; n = 7 Tg), and the third group of mice was treated with DSS as described above without AOM injection (n = 20 WT; n = 8 Tg). AOM alone represents treatment with the alkylating agent in the absence of inflammation and is expected to result in no tumor formation in WT mice at the dose used (25). DSS alone represents repeated cycles of inflammation and was included to assess whether inflammation alone caused dysplasia in these mice. The study was powered in such a fashion that the control arms required less mice as death before the end of the study was not anticipated for these treatment groups. Body weight, stool consistency, and stool occult blood was monitored during the DSS treatment and recovery phases. Upon sacrifice, colon was excised from the ileocecal junction to anus, cut open longitudinally, and prepared for histologic evaluation. To assess mortality, the same protocol was followed with the exception of extending through 126 days or until mice developed rectal prolapse and/or more than 20% body weight loss. Colons were assessed macroscopically for polyps using a dissecting microscope. Clinical score assessment Assessment of body weight loss, stool consistency, and the presence of occult/gross blood by a guaiac test (Hemoccult SENSA; Beckman Coulter) were determined daily during DSS administration to generate a clinical activity score as described previously (12). During recovery periods, body weight was measured every week for each group. Endoscopic assessment of polyp formation and polyp count Colonoscopy was done to assess polyp formation in mice by using the Coloview (Karl Storz Veterinary Endoscopy). Mice were euthanized with 1.5% to 2% isoflurane and approximately 3 cm of the colon proximal to the anus was visualized a