1. A method for inhibiting the progression of a mammalian non-small cell lung cancer (NSCLC) tumor belonging to a subset of NSCLC tumors in which PDGFRα is expressed, said method comprising (a) determining if a mammalian NSCLC tumor expresses PDGFRα and (b) if said tumor expresses PDGFRα, contacting said tumor with a PDGFRα-inhibiting therapeutic selected from the group consisting of Imatinib mesylate (STI-571), BAY 43-93006, XL-999 and SU11248.