The invention discloses a previously unidentified subset of mammalian non-small cell lung carcinomas (NSCLC) in which platelet-derived growth factor receptor alpha (PDGFRα) is expressed and is driving the disease, and provides methods for identifying a mammalian NSCLC tumor that belongs to a subset of NSCLC tumors in which PDGFRα is expressed, and for identifying a NSCLC tumor that is likely to respond to a PDGFRα-inhibiting therapeutic. The invention also provides methods for inhibiting the progression of a mammalian NSCLC tumor in which PDGFRα is expressed, and for determining whether a compound inhibits the progression of a PDGFRα-expressing mammalian NSCLC tumor.
