Early changes associated with the development of smoking-induced diseases, e.g., COPD and lung cancer (the two commonest causes of death in U.S.) are often characterized by abnormal airway epithelial differentiation. Airway basal cells (BC) are stem/progenitor cells necessary for generation of differentiated airway epithelium. Based on our preliminary observations on SAE BC cells and FGFR2 signaling, we hypothesized that suppression of FGFR2 signaling in the SAE BC stem/progenitor cells by cigarette smoking renders these cells less potent in generating and maintaining normally differentiated SAE, shifting these cells towards a COPD associated phenotype. To test this, SAE basal cells will be isolated from cultured cells obtained through bronchoscopic brushings and analyzed through in vitro assays for their stem/progenitor capacities.