Phosphorylation of CREB (cyclic AMP [cAMP]-response element [CRE]-binding protein) by cAMPdependent protein kinase (PKA) leads to the activation of many promoters containing CREs. In neurons and other cell types, CREB phosphorylation and activation of CRE-containing promoters can occur in response to elevated intracellular Ca 2+. In cultured cells that normally lack this Ca 2+ responsiveness, we confer Ca 2+-mediated activation of a CRE-containing promoter by introducing an expression vector for Ca 2+/calmodulin-dependent protein kinase type IV (CaMKIV). Activation could also be mediated directly by a constitutively active form of CaMKIV which is Ca 2+ independent. The CaMKIV-mediated gene induction requires the activity of CREB/ATF family members but is independent of PKA activity. In contrast, transient expression of either a constitutively active or wild-type Ca 2+/calmodulin-dependent protein kinase type II (CaMKII) fails to mediate the transactivation of the same CRE-containing reporter gene. Examination of the subcellular distribution of transiently expressed CaMKIV and CaMKII reveals that only CaMKIV enters the nucleus. Our results demonstrate that CaMKIV, which is expressed in neuronal, reproductive, and lymphoid tissues, may act as a mediator of Ca 2+-dependent gene induction.