Figure 6.

TGF-β1 induces the secretion and production of ET-1 via Smad- and ERK1/2-dependent pathways. Serum-starved adult HCFs were pretreated with 1 µM Smad inhibitor (Smad inh), 1 µM FR180204 (ERK inhibitor; ERK inh), or 1 µM SB203580 (p38 MAPK inhibitor; p38 inh) for 1 h before treatment with 1 ng/mL TGF-β1 for 24 (A) or 6 h (B). (A) After TGF-β1 treatment, the culture medium was collected. The amounts of ET-1 secreted into the culture medium were determined by ELISA. (B) Relative mRNA levels of ET-1 were analyzed by qRT-PCR. Data are expressed as the mean ± SEM (n = 4). * p < 0.05 vs. vehicle; ^# p < 0.05 vs. TGF-β1.