CCL2 and chronic obstructive pulmonary disease: The levels of MCP-1 were decreased after TGF-β stimulation of lung fibroblasts from control subjects at normoxic conditions (p = 0.023) and hypoxic conditions (p = 0.030) in fibroblasts from control subjects, and in fibroblasts from COPD patients at normoxic (p = 0.048) and hypoxic (p = 0.022) conditions (Fig. 4c).