MMP9 level is a valuable indicator of colorectal cancer patients who are at high risk of developing cancer recurrence [26], and increase of MMP9 expression has been shown to promote invasion and metastasis through activation of focal adhesion kinase/extracellular signal-regulated kinase/matrix metalloproteinase-9 axis in human hepatocellular carcinoma [27]. This evidence concerns the gene MMP9 and hepatocellular carcinoma.