ERK phosphorylation of StAR is required for the correct association of StAR with the mitochondria.

<p>Cells were transfected with an empty pRc/CMVi vector (mock) or containing the StAR wt cDNA (StAR wt) or StAR mutant form (StAR S232A). After 48 h, cells were stimulated for 1 h with <b>A.</b> hCG (20 ng/ml) or <b>B.</b> 8Br-cAMP (cAMP) (0.5 mM). Membranes were sequentially blotted for StAR and III Complex. Representative western blots are shown. For each band, the OD of the expression levels of StAR protein were quantified (arbitrary units) and normalized to the corresponding III Complex protein. The relative levels of StAR protein are shown: <b>A.</b> ***<i>p</i><0.001 vs. control mock; **<i>p</i><0.01 vs. control StAR wt; ### <i>p</i><0.001 vs. hCG StAR wt. <b>B.</b> ***<i>p</i><0.001 vs. control mock; **<i>p</i><0.01 vs. control StAR wt; ## <i>p</i><0.01 vs. cAMP StAR wt. Results are expressed as mean ± SEM of three independent experiments. Progesterone production was determined by RIA in the incubation media. Results are indicated in a Table at the bottom of each panel. Data are expressed as ng/ml of P4.