IGF1 and chronic obstructive pulmonary disease: Specifically, the increase of airway smooth muscle cell (ASMC) number occurring in asthma and in COPD may be, at least partially, caused by growth factors, such as the platelet-derived growth factor (PDGF), the epidermal growth factor (EGF), the insulin-like growth factor-1 (IGF-1), and the basic fibroblast growth factor (bFGF) [3].