Abstract: GCs were obtained from the ovaries of activity of DES-treated immature rats and cultured in serum-free medium. FSH receptor occupancy lesded to phosphorylation/activation of p38 MAPK in time-dependent manner. Phosphorylated p38 MAPK by FSH was observed within 5 min and reached the highest level at 30 min. Moreover, such activation was protein kinase A-dependent as indicated by the results using specific inhibitors.Interestingly.inhibition of p38 MAPK acitivity with SB203580 augmented estradiol production at the same time (p<0.01). RT-PCR data showed that inclusion of SB203580 in the FSH-stimulated FSH-induced STAR mRNA Production, while decreased the FSH-stimulated P450arom mRNA expression of STAR in mitochondria than FSH treatment alone.