Figure 1.

PM challenge induces TGF-β expression in a time- and dose-dependent manner. A. HBECs were challenged with PM (100 μg/ml) for 6 h, 24 h, or 48 h, and cell lysates were analyzed by western blotting for TGF-β protein expression. B. Bar graph of relative TGF-β levels. *, P<0.05 compared to control. C. HBECs were exposed to different concentrations of PM for 48 h (0-100 μg/ml), and TGF-β protein expression levels were assayed by western blotting. D. Bar graph of relative TGF-β levels. *, P<0.05 compared to control. PM, particulate matter; HBECs, human lung epithelial cells.