Fig. 5

GDF-11 does not activate SMAD1/5/8, ERK1/2, and AKT signaling pathways in hGL cells. A and B, hGL cells were pretreated with vehicle control (DMSO), 1 µM dorsomorphin (DM) (A) or 1 µM DMH-1 for 1 h, and then treated with 30 ng/mL GDF-11 (G11) for 24 h. The mRNA levels of StAR were determined by RT-qPCR. C, hGL cells were treated with 30 ng/mL GDF-11 (G11) for 30 and 60 min. The levels of phosphorylated SMAD1/5/8 and the total SMAD1 were determined by western blot. Protein lysate from hGL cells treated with 10 ng/mL BMP-4 (B4) for 60 min was used as a positive control for the phosphorylation of SMAD1/5/8. D, hGL cells were treated with 30 ng/mL GDF-11 (G11) for 10 and 30 min. The levels of phosphorylated and total forms of ERK1/2 and AKT were determined by western blot. Protein lysate from hGL cells treated with 100 ng/mL amphiregulin (AREG) for 30 min was used as a positive control for the phosphorylation of ERK1/2 and AKT. The RT-qPCR results are expressed as the mean ± SEM of at least three independent experiments. The values without a common letter are significantly different (p < 0.05)