Previous studies have shown that NUAK1 activates MT1-MMP, which results in promoting the metastasis of breast and pancreatic cancer via activation of MMP-2 and MMP-9 [42,46], so miR-203-driven invasion of HNSCC cells may be regulated by a pathway that is distinct from EMT induction. Here, MMP9 is linked to head and neck squamous cell carcinoma.