Matrix metalloproteinases (MMPs) are a family of zinc- and
calcium-dependent proteolytic enzymes. In humans, 23
MMPs are described, and they are either membrane-
anchored or secreted [1]. These enzymes are made up of different domains, modules, and motifs which are the basis
for their classification and are important for their substrate
specificity, their localization, and interactions with other mac-
romolecules. All MMPs contain an N-terminal signal peptide
which directs the enzymes to the secretory pathway, a pro-
domain that interacts with the active site and thereby confers
the latency of the enzymes and a catalytic domain with a zinc
ion in the active site. Most of the MMPs also contain a C-
terminal hemopexin-like domain that is linked to the catalytic
domain through a hinge region. The membrane-bound MMPs
and three of the secreted MMPs (MMP-11, MMP-21,
and MMP-28) contain a short basic motif at the end of
their pro-domain and can be activated by the serine
protease furin prior to secretion