MMP9 and endometriosis: The initial phase of endometriosis is an invasion event that requires ECM breakdown and tissues repair, which requires the increased activity of MMP-1, MMP-2 and MMP-9.31 Indeed, MMPs and TIMPs levels have been correlated with the development and progression of endometriosis.31,32 Prostaglandins (PGs) are bioactive lipids produced from arachidonic acid by cyclooxygenase (COX) enzymes and a specific terminal prostanoid synthetase enzyme.