Only a single study has examined ATM inhibition (GSK635416A) in HNSCC cells [19], although this demonstrated increased radiosensitivity in five HPV-negative HNSCC cell lines (UTSCC2, UTSCC8, UTSCC24A, UTSCC36 and UTSCC40), which is comparable with our data. The gene discussed is ATM; the disease is head and neck squamous cell carcinoma.