Disclosed is the identification, provision and use of a panel of biomarkers that predict sensitivity or resistance to gefitinib and other EGFR inhibitors, and products and processes related thereto. Specifically, a method is described for selecting a cancer patient who is predicted to benefit from therapeutic administration of an EGFR inhibitor, an agonist thereof, or a drug having substantially similar biological activity as EGFR inhibitor. Also described is a method to identify molecules that interact with the EGFR pathway to allow or enhance responsiveness to EGFR inhibitors, as well as a plurality of polynucleotides or antibodies for the detection of the expression of genes that are indicative of sensitivity or resistance to EGFR inhibitors, an agonist thereof, or a drug having substantially similar biological activity as EGFR inhibitors. A method to identify a compound with the potential to enhance the efficacy of EGFR inhibitors is also described.