(A) Athymic nude mice with PC9/BR polyclonal tumors were administered vehicle, afatinib, panitumumab, or afatinib plus panitumumab. Points, values from five mice per group; bars, SE. *, P < 0.05, for the combination of afatinib plus panitumumab versus either afatinib or panitumumab alone. (B) MRI images of lungs from a tumor-bearing C/L+T mouse pretreatment and after treatment with the combination of afatinib plus panitumumab (pani) for 2 weeks (2W). H&E-stained section from a treated C/L+T mouse (right panels) (C) PC9/BRc1 cells were plated in soft agar and treated with afatinib (B), cetuximab (C), panitumumab (P), or either a combination of afatinib plus cetuximab or afatinib plus panitumumab for 8 days, after which absorbance levels were measured. Data are means ± SD of triplicates from an experiment that was repeated a total of 3 times with similar results. (D) Cells were serum starved for 12 hours prior to treatment with the indicated drugs for 8 hours, after which cell lysates were subjected to immunoblot analysis with antibodies against the indicated proteins.