In this work, the scientists analyzed the expression of different members of the plasminogen activator and MMPs systems of endometriosis and found that the ovarian endometriosis tissues had higher levels of inhibitor of plasminogen activator 1 (Plasminogen Activator Inhibitor-PAI-1) and TIMP-1, compared to normal endometrium. This evidence concerns the gene SERPINE1 and endometriosis.