Effects of different concentrations of AFB1 on the mRNA expression of antioxidant-related genes including (A) CAT and (B) GPX1 in canine small intestinal epithelial primary cells. Data are presented as the mean ± SEM (n = 4). Different letters (a, b, and c) above the bars indicate significant differences between means. ab and ac indicate insignificant difference. AFB1, aflatoxin B1; CON, control; CAT, catalase; GPX1, glutathione peroxidase 1.