Intestinal mucositis was induced by subcutaneous administration of MTX. After sacrifice, on the 5th day, a sample of the jejunum segment was harvested for MPO activity assay. *p < 0.05 represents statistical differences compared to iNOS+/+/control group. The number of animals in each group was at least four. Data were analyzed by using analysis of variance (ANOVA) and Bonferroni tests.