Fig. 4.

Activation of ERK1/2 signaling is required for the RSV-induced StAR expression. A, KGN cells were treated with 1 μM RSV for 10 min. The levels of phosphorylated and total forms of ERK1/2 and AKT were determined by Western blot. KGN cells treated with 10 ng/mL amphiregulin (AREG) for 10 min were used as positive controls for the activations of ERK1/2 and AKT signaling pathways. B, Primary hGL cells were treated with 3 μM RSV for 10 min. The levels of phosphorylated and total forms of ERK1/2 were determined by Western blot. C and D, KGN (C) and primary hGL (D) cells were pretreated with vehicle control (DMSO) or 1 μM U0126 for 1 h, and then treated with RSV (1 μM for KGN cells and 3 μM for primary hGL cells) for 24 h. The StAR protein levels were examined by Western blot. E, KGN cells were transfected with 50 nM control siRNA (si-Ctrl) or ERK1+ERK2 siRNAs (si-ERK1/2) for 48 h, and then treated with 1 μM RSV for 24 h. The StAR and ERK1/2 protein levels were examined by Western blot. The results are expressed as the mean ± SEM of at least three independent experiments. Values that are statistically different from one another ( p < 0.05) are indicated by different letters.