PLAU and head and neck squamous cell carcinoma: PLAU is a protease involved in numerous different signaling pathways, including apoptosis, epithelial-mesenchymal transition (EMT), and Ras/MAPK; hypomethylation of PLAU gene as well as hypomethylation and subsequent downregulation of miR-23b-3p, a microRNA that targets PLAU, may be responsible for the overexpression and the oncogenic role of PLAU in HNSCC [30].