MMP9 and colorectal cancer: Numerous experimental studies based on gelatine zymography and immunohistochemistry methods have demonstrated higher expression of mainly MMP-2 (inactive pro-MMP-2 and active MMP-2 forms) and MMP-9 (pro-MMP-9 and MMP-9) enzymes within colorectal cancer mass and dysplastic adenomas compared to the corresponding normal mucosa of the large intestine [6,7,8,9].