This cyclic CTT Gelatinase Inhibitor peptide is an inhibitor for matrix metalloproteinases (MMP)-2 and MMP-9. It is also called type IV collagenase or gelatinase. Gelatinases are potential targets of therapeutic intervention in cancer, and inhibitors of these enzymes can prevent tumor progression. Cyclic CTT inhibits the migration of human endothelial cells and tumor cells. It prevents tumor growth and invasion. Inhibitors, complexed with their target proteinases, can be taken up into cells by endocytosis, and CTT added to liposomes enhances their uptake by tumor cells, thus providing possibility of liposomal delivery of chemotherapeutic agents. MMP-2 inhibition with cyclic CTT is also important in hypoxia studies.