On this basis, the aim of this study was not only to assess VEGF levels in induced sputum of healthy smokers and of smokers with bronchitis type of COPD, but to further assess smoking as a potential cause of raised airway VEGF levels in bronchitis type of COPD, and to test the association between VEGF levels in induced sputum and airway inflammation in these subjects. This evidence concerns the gene VEGFA and bronchitis.