MMP9 and ovarian neoplasm: Further supporting a link between metformin and metastatic potential, we found that metformin significantly inhibited adhesion and invasion in all four OC cells tested and led to a decrease in matrix metalloproteinase-9 (MMP-9) in ovarian tumors in the KpB mice, an enzyme intricately linked to extracellular matrix remodeling and angiogenesis.