Moreover, the expression of MMP-9 (a Matrix Metalloproteinase associated with EMT), PGE2 (a product activated by COX-2 associated with OSCC metastasis), VEGF (the most important angiogenic factor in HNSCC), and CXCL8 are also associated with different genes associated with metastasis, especially MMP-9 (a matrix metalloproteinase associated with EMT). This evidence concerns the gene MMP9 and head and neck squamous cell carcinoma.