EGFR and head and neck squamous cell carcinoma: To investigate the possible effects of EGFR genetic alterations on the sensitivity of HNSCC cell lines to the EGFR-directed antibody cetuximab, the EGFR specific tyrosine kinase inhibitor (TKI) erlotinib, the RAS inhibitor zoledronic acid, and the c-MET inhibitor SU11274, we chose two cell lines, the PE/CA-PJ15 harboring one R521K mutant allele of EGFR (heterozygous) and the PE/CA-PJ41 cell line expressing only wild type EGFR (homozygous wild type, Figure 1A).