Consistent with previous literature showing that increased MMP9 expression promotes cancer cell migration, invasion, and metastasis [42], MMP9 mRNA levels were enhanced in N1 + (Fig. 6H) and advanced-stage (III + IV) (Fig. 6I) tumors when compared to those in N0 and the earlier-stage (I + II) tumors, respectively. This evidence concerns the gene MMP9 and cancer.