PIK3CA and head and neck squamous cell carcinoma: Panel of HNSCC cell lines showing growth-inhibition effects of dacomitinib and cetuximab, mutation status of K-RAS and PIK3CA hotspots (as detected by PCR and sequencing), EGFR amplification status as detected by FISH (presented as ratio of EGFR gene to centromere 7), and anatomical category of original tumor primary site.