The present invention provides protein and gene expression profiles indicative of whether a patient afflicted with non-small cell lung cancer is likely to be responsive to treatment with a therapeutic compound that is a EGFR-TK inhibitor. By identifying such responsiveness, a treatment provider may determine in advance those patients who would benefit from such treatment, as well as identify alternative therapies for non-responders. The present invention further provide methods of using the gene and protein expression profiles, and assays for identifying the presence of a gene or protein expression profile in a patient sample.