TGFB1 and chronic obstructive pulmonary disease: Zanini et al.38 compared BB from ex-smokers with COPD who had quit for longer than 10 years with controls and did not find any difference in the number of vessels, but the vascular area was larger and VEGF-positive cells, transforming growth factor-positive (TGF-β) cells and fibroblast growth factor (FGF)-positive cells were increased in COPD.