Matrix metalloproteinases (MMPs) are responsible for the degradation of extracellular matrix proteins. MMPs are essential for tissue remodeling during normal processes such as embryonic development as well as pathological conditions such as arthritis and tumor metastasis. MMP3, a member of the stromelysin family, has broad specificity for proteins such as collagens, fibronectin, proteoglycans, and elastin making it an important player in extracellular matrix remodeling. These activities are especially important during tumorigenesis by enhancing epithelial to mesenchymal transition.