Cyclic AMP response element (CRE)-binding protein (CREB) is a transcription factor that regulates and responds to diverse cellular responses, ranging from proliferation, survival, differentiation, stress responses, and neuronal activity.  These cellular signals lead to upstream kinase activation, such as protein kinase A (PKA), pp90 ribosomal S6 kinase (pp90RSK), and Ca2+/calmodulin-dependent protein kinases (CaMKs), and these kinases in turn phosphorylate CREB to induce CREB activity.  CREB increases the transcription of genes that contain cAMP responsive elements. 

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Signosis has developed CREB luciferase reporter HEK293 stable cell line by co-transfecting CREB luciferase reporter vector and hygromycin expression vector.  The hygromycin resistant clones were subsequently screened for forskolin-induced luciferase activity.   The cell line can be used as a reporter system for monitoring the activation of CREB triggered by stimuli treatment, such as forskolin and gene overexpression and gene knockdown.