“…The important role that MMP-9 plays in reactive processes including inflammation and wound repair explains why the enzyme is constitutively expressed only by a few cell types, such as neutrophils and macrophages [ 4 , 17 ]. Other cells (including fibroblasts, osteoblasts and epithelial, endothelial, dendritic and T cells) produce MMP-9 primarily upon stimulation with inflammatory cytokines, chemokines, or growth factors [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Among the inducers of MMP-9 expression are interleukin-1, tumor necrosis factor α, epidermal growth factor, transforming growth factor β1, vascular endothelial growth factor (VEGF) and the CXC chemokine ligand 12 (CXCL12) ( Figure 1 ) [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”