MMP-13 (Matrix metalloproteinase 13), also known as collagenase-3, cleaves type I collagen and was previously thought to be the rodent analogue of human interstitial collagenase (MMP-1). MMP-3 is also known to activate several other MMPs such as MMP-7 and MMP-9. All the above make it a crucial factor in connective tissue remodeling. MMP-13 is found in hypertrophic and calcifying cartilage of mammalian growth plate. It can be detected 3 bands that the glycosylated pro MMP-13 (70 kDa), unglycosylated proform (55 kDa), and active MMP-13 enzyme (40kDa) by western blot.