MPO and colitis: After necropsy, examination of the colon found that during the acute colitis Acer3−/− mice had earlier and greater colonic shortening, compared with Acer3+/+ mice (Figures 5f and g), higher scores of colonic epithelial damage and inflammatory infiltration (Figures 5h and i), and a greater colonic myeloperoxidase (MPO) activity (Figure 5j).