All tissues and cell types are surrounded by an extracellular matrix or ECM. So, degradation of ECM is necessary to make space for the cells to proliferate and migrate. Cells do so by secreting matrix metalloproteases or MMPs, specialized enzymes which hydrolyze proteins and glycoproteins present in the ECM. MMPs are a large family of proteins classified based on their substrate affinity, but all of them share several common features, such as an active site with three conserved histidine residues bound to a zinc ion. Additionally, most MMPs are active at neutral pH. Collagenase, the most common MMP cleaves fibrillar collagen in two steps. First, collagenase unwinds the triple helical structure of collagen at a specific site and degrades the peptide bonds. This denatured collagen, called gelatin, is further degraded by gelatinase into smaller fragments. However, the activity of MMPs must be tightly regulated to avoid unnecessary ECM degradation. For instance, cells produce specific protease inhibitors that can inhibit MMP activity when not required.