Fig. 5.

Activation of ERK1/2 signaling is required for the HB-EGF-induced StAR expression. A and B, KGN cells were pretreated with vehicle control (DMSO), 10 µM U0126 or 10 µM LY294002 for 1 h, and then treated with 5 ng/mL HB-EGF (HB) for 24 h. The StAR mRNA levels (A) and protein levels (B) were examined by RT-qPCR and western blot, respectively. C and D, Primary hGL cells were pretreated with vehicle control (DMSO) or 10 µM U0126 for 1 h, and then treated with 5 ng/mL HB-EGF (HB) for 24 h. The StAR mRNA levels (C) and protein levels (D) were examined by RT-qPCR and western blot, respectively. 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