3'-5'-cyclic adenosine monophosphate (cAMP) is a second messenger central to a number of biological processes. It is produced by the catalytic action of adenylyl cylcase (AC) on ATP. AC activity is regulated via its interaction with activating (Gαs) or inhibiting (Gαi) G-proteins.PKA is an important target of cAMP activation. PKA consisting of a catalytic and a regulatory subunit. Each regulatory subunit is bound by two molecules of cAMP which then allows the catalytic subunit to phosphorylate target proteins like the transcriptional regulator CREB. cAMP also activates EPAC1, a Rap-specific guanine nucleotide exchange factor which lead to the activation of ERK. Gαo and Gαi mediated cAMP activation of Src and Stat3 pathways in transformation of cells has also been reported.