MMP-2 (gelatinase A) is primarily expressed in mesenchymal cells (mainly fibroblasts) during development and tissue regeneration. Human and mouse MMP-2 are secreted as 72 kDa proenzymes of 631 and 662 amino acids, respectively. The removal of the pro domain can be initiated by membrane-type MMPs or by serine proteases such as thrombin and activated protein C. The resulting mature and active enzyme consists of a catalytic domain, which is interrupted by three contiguous fibronectin type II-like domains, and a C-terminal, hemopexin-like domain. TIMPs inhibit active MMP-2 through tight, but non-covalent binding of their N-terminal domains to the catalytic domain of MMP-2 in a 1:1 stoichiometry. In addition, TIMP-2 can bind to the proenzyme through interaction between the C-terminal domains of both proteins.