– Matrix metalloproteinase-12(MMP12) is a secreted protein.It contains 4 hemopexin repeats and belongs to the peptidase M10A family. MMP12 may be involved in tissue injury and remodeling and have significant elastolytic activity. It can accept large and small amino acids at the P1′ site, but has a preference for leucine. Aromatic or hydrophobic residues are preferred at the P1 site, with small hydrophobic residues (preferably alanine) occupying P3.