MMP7 and hepatocellular carcinoma: Originally, extracellular MMP-7 is engaged in the disintegration of Fas ligand, which induces cell invasion that has an anti-apoptotic effect.40 Moreover, studies have shown that MMP-7 reduces the ability of natural killer (NK) cells, a part of the immune system, to recognize cancer cells, so the immune system cannot kill tumor cells.3 Recent study conducted by Zeng et al. 41 showed that the level of S1P (sphingosine-1-phosphate) induces significant elevation of MMP-7 in hepatocellular carcinoma metastasis.