Metalloproteinase inhibitor 1, also known as Tissue inhibitor of metalloproteinases 1, Fibroblast collagenaseinhibitor, Collagenase inhibitor, CLGI and TIMP1, is a secreted protein which belongs to the proteaseinhibitor I35 (TIMP) family. TIMP1 complexes with metalloproteinases (such as collagenases) andirreversibly inactivates them by binding to their catalytic zinc cofactor. TIMP1 also mediates erythropoiesis. Unlike IL-3, it is species-specific, stimulating the growth and differentiation of only human and murineerythroid progenitors. TIMP1 is known to act on MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-11, MMP-12, MMP-13 and MMP-16. TIMP1 does not act on MMP-14. Excessive TIMP1 wasdeleterious to ovulation and embryo development. Novel TIMP1 modulating therapies may be developed toalleviate infertility in women with endometriosis. Tissue inhibitors of metalloproteinases (TIMP) family are natural inhibitors of the matrix metalloproteinases(MMPs) , the zinc enzymes involved in extracellular matrix maintenance and remodeling. The TIMP familyencompasses four members ( TIMP1, TIMP2, TIMP3, TIMP4) , and the inducible form TIMP1 is aglycoprotein expressed by a variety of cell types. It inhibits most MMPs except membrane-type MMPsubfamily by forming non-covalent binary complex, but also interacts with the hemopexin-like (PEX) domainof pro MMP-9. TIMP1 has been identified as a multifunctional molecule with divergent functions. It exhibitskeratinocyte and fibroblast growth factor-like activity and acts as a cell survival factor, and additionallyparticipates in tumor metastasis, angiogenesis, inflammatory responses, as well as CNS homeostasis. Thus, TIMP1 overexpression may serve to help identify patients with particularly aggressive disease for adjuvanttreatments.