Stimulation of pheochromocytoma PC12 cells by cAMP-elevating agents caused the induction of the immediate early gene 3CH134, which encodes MAP kinase phosphatase-1 (MKP-1). Forskolin was as potent as serum in stimulating MKP-1 gene expression, whereas dibutyryl-cAMP and neuropeptide PACAP were less effective. Induction of the MKP-1 gene was accompanied by neo-synthesis of MKP-1 protein. MAP kinase activation was not involved in the cAMP-induced MKP-1 gene expression. The MAP kinase inactivation, that would result from MKP-1 induction in response to increased intracellular cAMP level, contributes to explain how hormones or neurotransmitters signaling through cAMP influence cell growth and differentiation.
