Figure 3From: Vascular endothelial growth factor: an angiogenic factor reflecting airway inflammation in healthy smokers and in patients with bronchitis type of chronic obstructive pulmonary disease?Levels of TNF-α (pg/ml), expressed as median values (inter-quartile range) in induced sputum of healthy non-smokers (A), asymptomatic smokers (B) and COPD smokers (C). *p < 0.05, for healthy non-smokers vs COPD smokers.Back to article page