Caffeine, rolipram, and db-cAMP inhibit TGF-β1 induced Smad-signalling in lung epithelial cells.

<p>The TGF-β1–sensitive (CAGA)₁₂-luciferase reporter construct was transiently transfected into A549 cells. Cells were then treated with TGF-β1 (10 ng/ml) and/or different concentrations of caffeine (A), rolipram (B), or db-cAMP (C). Firefly luciferase activity was normalized to the activity of Renilla luciferase under control of the thymidine kinase promoter. Relative luciferase activity compared to controls is shown. * p<0.05 compared to control cells, # p<0.05 compared to TGF-β1 treated cells.