TGFB1 and chronic obstructive pulmonary disease: The agents utilised were bradykinin (elevator of intracellular Ca2+), forskolin (activator of adenylyl cyclase and hence the pro-relaxant cyclic AMP pathway), lipopolysaccharide (LPS) (used as a mimic of bacterial infection), transforming growth factor β1 (TGFβ1) (a key cytokine, found to be elevated in airway inflammation, and in COPD) and the Extracellular Signal-Regulated Kinase (ERK) inhibitor U0126.