MMP9 and hepatocellular carcinoma: Other studies also favor the significance of cytokine CCL2 in invasiveness and migration of tumor cells such as prostate cancer cells [22,23], breast cancer cells [24] etc. In addition, myofibroblasts-secreted CCL2 also enhances the malignant phenotypes of HCC cells by upregulating MMP2 and MMP9 expression [25], all signs as mentioned above suggest CCL2 involves in pathological development of tumor.