EGFR and head and neck squamous cell carcinoma: Overexpression of EGFR could be detected in over 90% of HNSCC, which was an important signal receptor that brings about tumorigenesis, proliferation, and metastasis through downstream pathways, including PI3K/AKT and MAPK (Nicholson et al., 2001; Citri and Yarden, 2006).