Four-micron-thick sections were prepared from formalin-fixed, paraffin-embedded colon tissue from AOM/DSS-treated mice and stained with H&E. Immunohistochemical staining against BrdU, PCNA, IL-1β, IL-6, NF-κB and Nrf2 was performed with standard techniques. Image pro plus software was used to analyze the number of positive cells by detecting IOD.