RAPGEF3 and pemphigus: In contrast, higher cAMP levels in response to treatment with the combination of the adenylate cyclase activator forskolin and the PDE4 inhibitor rolipram ameliorated AK23-induced loss of adhesion in WT as well as in Epac1-ko cells (Figure 3B and Supplemental Figure 3, C and D), indicating that different downstream molecules are involved in protective cAMP signaling in pemphigus.