TGFB1 and chronic obstructive pulmonary disease: The levels of VEGF-A were significantly increased after TGF-β exposure in lung fibroblasts from healthy subjects both at normoxic (p = 0.0087) and hypoxic (p = 0.015) conditions and COPD patients at normoxic (p = 0.015) and hypoxic conditions (p = 0.0047) (Fig. 3a).