CREB (cAMP-responsive element binding protein), which can be activated after phosphorylation by protein kinase A, plays an important role in cAMP-induced gene expression. Several recent studies have suggested that a co-activator designated as CREB binding protein (CBP) is crucial in mediating the transcriptional activity of CREB. In nervous system, in addition to playing a role in neurotransmitter-induced gene transcription, CREB may take part in mediating neurotrophin signals that ultimately lead to such cellular responses as proliferation, differentiation and survival.