MMP9 and gastric cancer: Its mechanism of action is pleiotropic, and it is based on the induction of extrinsic and intrinsic apoptotic pathways, a decrease of mitochondrial membrane potential as well as inhibition of proteins responsible for increased proliferation and invasion of gastric cancer cells with overexpressed MUC1, such as mTOR, sICAM1 and MMP-9 (Figure 16).