Airway remodeling with inflammatory cell infiltration, epithelial shedding, basement membrane thickening and increased mass of airway smooth muscle (ASM) is an important determinant of bronchial obstruction and hyperresponsiveness in asthma.1,2 Increased ASM mass is by far the most important abnormality responsible for excessive airway narrowing and compliance of the airway wall in asthma.1-3 ASM growth and proliferation in asthma is a complex phenomenon of which the underlying mechanisms are difficult to investigate in vivo. The increased amount of ASM in asthmatics is an indication of abnormal cell proliferation and growth, but little is known regarding the molecular mechanisms and factors that regulate ASM cell proliferation and growth in asthma.