Fig. 6. The role of ERK in SPC-induced expression of -SMA and delayed phosphorylation of Smad2. (A) Serum-starved hATSCs were treated with 2 µM D-erythro-SPC or 2 ng/ml TGF-ß3 for the indicated time periods. (B) hATSCs were pretreated with 100 ng/ml PTX for 24 hours, and then exposed to 2 µM D-erythro-SPC for 10 minutes. (C) hATSCs were pretreated with 10 µM U0126 for 15 minutes, and then exposed to 2 µM D-erythro-SPC or 2 ng/ml TGF-ß3 for 4 days. (D) hATSCs were pretreated with 10 µM U0126 for 15 minutes, and then exposed to 2 µM D-erythro-SPC or 2 ng/ml TGF-ß3 for 10 minutes. The expression levels of -SMA, actin, and ERK were determined by western blotting with anti--SMA, anti-actin and anti-ERK antibodies, respectively. The phosphorylation levels of ERK and Smad2 were determined by western blotting with anti-p-ERK and anti-p-Smad2 antibodies, respectively. Representative data from three independent experiments are shown.