Fig. 4.

Curcumin inhibits TGF-β-induced phosphorylation (p) of Smad2, Smad3, and extracellular signal-regulated kinase (ERK) 1/2 in lung fibroblasts. Human fibroblasts obtained from histologically normal lungs (n = 4) were treated with curcumin (20 μM) for 2 h followed by TGF-β (2 ng/ml) for varying periods. Cell lysates were subjected to SDS-PAGE followed by immunoblotting with antibodies against pS465/467 Smad2 (A) and pS423/425 Smad3 (B). Blots were probed first with phosphospecific Smad antibodies, stripped, and reprobed with GAPDH. Mean densitometric data are also presented. *P < 0.05 vs. 0 μM at each respective time point. C: pERK and total ERK were measured by Bio-Plex, and their ratio was determined. *P < 0.05 vs. 0 μM at each respective time point.