MMP9 and cancer: Since type IV collagenase matrix metalloproteinases, especially MMP-2 and MMP-9, have been found to promote invasion and metastasis of malignant tumors, we investigated the relative inhibitory effects in MMP-2 and -9 by EGCG, the main polyphenol in green tea extract (GTE) to that of GTE and to that of NM as a whole using four cancer cell lines expressing MMP-2, MMP-9 or both, to determine if there is an additive or synergistic effect from combinations of these agents [107].