MMP9 and inflammatory bowel disease: During IBD, MMP2 is highly upregulated and localizes to the subepithelial and pericryptal fibroblasts/myofibroblasts, mononuclear cells (macrophages and lymphocytes), epithelial cells and vascular endothelial cells, while MMP9 is expressed by immune cells (neutrophils, macrophages, lymphocytes) as well as by epithelial cells during inflammation [51].