Wild type and AKR1B8 −/− mice (n=15 each) were administered with dextran sulfate sodium in drink water to induce colitis as described in Materials and Methods. (A) A palpable tumor (arrow) from an AKR1B8 −/− mouse. (A-1), H&E histology. (B) Summary of colitis-associated dysplastic lesions. *, P<0.05 and **, P<0.01 compared to wild type control. Statistical significance was tested by Student’s t test. (C) Grade and aggressiveness of dysplasia: Upper panel, H&E histology; middle panel, PCNA expression; and lower panel, BrdU labeling (1 hour). Scale bar, 100µm.