The present invention relates to a method of determining whether a biological sample comprising human lung cancer cells is sensitive to a combination of an epidermal growth factor receptor inhibitor and a chemotherapeutic agent by determining the overexpression of a phosphorylated AKT protein and/or a phosphorylated MAPK protein in the biological sample. The invention is also related to methods for deriving a candidate agent or for selecting a composition for inhibiting the progression of lung cancer in a patient wherein a phosphorylated AKT protein and/or a phosphorylated MAPK protein is used.