A and B, the PKA inhibitor H-89, the PKC inhibitor GF-109203X (A) and the calcium chelator BAPTA-AM (B) all enhance the response to VIP in pancreatic acini. W-7, which is a calmodulin inhibitor, and FK-506, which is a calcineurin inhibitor, do not modify the response to VIP (B). C, the calcium ionophore A23187, the phorbol ester PMA and the muscarinic agonist carbachol do not modify VIP-stimulated cAMP generation. GF, GF-109203X; CCh, carbachol. Values are means ± SEM; n = 5 mice. *P < 0.001 vs. control; †P < 0. 001 vs. VIP alone.