The colonic antioxidant milieu of rats challenged with acetic acid-induced colitis was further characterized by exploring the colonic Nrf2/Keap-1 pathway by detecting the immunostaining of the nuclear factor erythroid 2-related factor 2 (Nrf2) and the gene expression of its inhibitory unit Kelch-like ECH-associated protein-1 (Keap-1). The gene discussed is KEAP1; the disease is colitis.