TGFB1 and head and neck squamous cell carcinoma: Subsequently, NM has been proven to downregulate the expression of both matrix metalloproteinase−2 (MMP-2) and−9, vascular endothelial growth factor (VEGF) and transforming growth factor beta 1 (TGF-β1), secreted by tumor cells in head and neck squamous cell carcinoma, and NM inhibits angiogenesis and tumor invasion (9).