**1. Introduction**

Matrix metalloproteinases (MMPs) were first described by Gross fifty years ago. They are a family of zinc-dependent endopeptidases. They comprise a group of 25 enzymes. Metalloproteinases were first described as proteases degrading extracellular matrix (ECM) proteins such as collagens, elastin, proteoglycans and laminins, hence they were named matrix meatalloproteinases. MMPs were divided according to their substrate specificity into collagenases, gelatinases, stromolysins and matrilysins. This classification was later replaced by numbering the enzymes according to the chronology of their identification. Metalloproteinases are also called metalloproteases.

Four metalloproteases (MMP-14, MMP-15, MMP-16 and MMP-24) have a transmembrane and cytosolic domains. They constitute a subgroup of membrane-type metalloproteases (MT-MMPs) [1, 2].
