A, Serum-starved RSF were stimulated with 8-CPT-2-O-Me-cAMP (Epac-specific cAMP analog, 500 μM) and 6-Bnz-cAMP (PKA-specific cAMP analog, 500 μM) for 45 min. Lysates from the cells were subjected to Rap1 pull down assay. B, Serum-starved RSF were stimulated with 8-CPT-2-O-Me-cAMP (Epac-specific cAMP analog, 500 μM) and 6-Bnz-cAMP (PKA -specific cAMP analog, 500 μM) for 10 min. Levels of phospho-CREB and total CREB were analyzed by Western blotting. Blots are representative data and values are expressed as means ± standard errors from the indicated number of patients with RA in each panel.