MMP9 and cancer: Since rapid metastization is the major contributor to cancer mortality [2], its mediators have become one of the most important therapeutic goals, particularly a group of matrix metalloproteinases (MMPs) named MMP-2 and MMP-9, which are important regulators to the key processes underlying metastasis, including cell adhesion, spreading, migration, invasion and angiogenesis, and pre-cancer inflammatory diseases such as colitis [3,4].