Irradiation as well as treatments with erlotinib and cetuximab were described previously (6 (link)). NU7026 (EMD Millipore, 260961), hesperadin (Selleck, S1529), Gö6976 (LC Laboratories, G-6203), and AZD6244 (Selleck, S1008) were dissolved in dimethyl sulfoxide (DMSO) and chloroquine (Sigma, C6628) was dissolved in double distilled water. Drugs were added 1 hour prior to irradiation and maintained for the duration of each experiment. Chaetocin (Cayman, CAS 28097) and Ro-32-0432 (Merck, 557525) were dissolved in DMSO and incubated with cells for 1 hour before collecting for cell lysates. Thymidine (Sigma, T1895) was dissolved in PBS, and used at 2.5 mM concentration 16 hours before and 8 hours after releasing cells in normal cell culture medium.