Clone REA131 recognizes the serine 133 (S133)–phosphorylated form of the human cAMP responsive element (CRE)–binding transcription factor CREB, a member of a family of cAMP responsive element (CRE)–binding transcription factors that include CREB, CRE modulator (CREM), and activating transcription factor 1 (ATF1). REA131 cross-reacts with the S63-phosphorylated form of human ATF-1. Several different serine-threonine kinases have been shown to promote phosphorylation of CREB at its transcription activating site, S133, including a cAMP-dependent protein kinase A (PKA), protein kinase C (PKC; including PKCε), calmodulin kinases (CaMKs; e.g., CaMK-IV), and pp90 ribosomal S6 kinase (pp90 RSK; also known as RSK2). Once serine 133 of CREB is phosphorylated, CREB interacts with its co-activator protein, CREB-binding protein (CBP), or p300 to initiate transcription of CREB-responsive genes. CREB has been shown to be involved in a variety of cellular processes, including cell proliferation, survival, differentiation, adaptive responses, glucose homeostasis, spermatogenesis, circadian rhythms, and synaptic plasticity associated with memory. CREB plays many different roles in immune function, e.g., through the inhibition of NF-κB activity, the induction of IL-10 and the promotion of FoxP3 expression. CREB promotes activation and proliferation of T and B cells and differentially regulates Tʜ1, Tʜ2, and Tʜ17 responses. CREB is expressed in all somatic cells. 

Additional information: Clone REA131 displays negligible binding to Fc receptors.