Matrix metalloproteinases (MMP’s) belong to a family of secreted or membrane-associated zinc endopeptidases capable of digesting extracellular matrix components. This recombinant mouse MMP-9 has a purity of >90% on SDS-PAGE and becomes highly active when incubated with APMA. It can be used in FRET-based enzyme activity assay or served as positive control for zymography, Western blot, IP, and ELISA.