Involvement of protein kinase pathways in the regulation of marker genes in differentiating theca cells. Bovine theca cells were cultivated for 11 days in the presence of minimal amounts of insulin (100 ng/ml) and 10 ng/ml bovine luteinizing hormone and subsequently treated with different amounts of specific inhibitors for protein kinase A (H89, squares), RAF1 kinase (GW5074, triangles) or MAP kinase-kinase (PD 98059, circles). After 72 hours, CYP11A1, STAR, and INSL3 transcripts were quantified by real time-PCR as described in Materials and Methods. The results of one representative out of three experiments are shown. Data are expressed as mean ± standard deviation. Significant differences (P < 0.05) to the uninhibited control cultures are indicated by asterisks.