5-ASA failed to suppress OXZ colitis (supplementary Fig. 2E), whereas prednisolone significantly decreased the DAS, the CDS and myeloperoxidase (MPO) activity (DAS: 2.4 ± 1.2, CDS: 2.3 ± 0.5, MPO activity: 0.9 ± 0.3 kunits/gwwt) in OXZ mice compared with vehicle-treated OXZ mice (DAS: 6.9 ± 2.1, CDS: 5.2 ± 1.4, MPO activity: 3.2 ± 0.4 kunits/gwwt) (supplementary Fig. 2F). This evidence concerns the gene MPO and colitis.