Earl Sutherland discovered it and determined many of its functions, one of the most important of which is activation of protein kinase A. Pertussis toxin generally decreases levels of this compound, while cholera toxin generally increases it by permanently activating a G protein.  
In slime mold amoebas, starvation induces secretion of this compound, causing the amoebas' walls to stick together end-to-end. Earl Sutherland discovered it and determined many of its functions, one of the most important of which is activation of protein kinase A. Pertussis toxin generally decreases levels of this compound, while cholera toxin generally increases it by permanently activating a G protein.  Its production inside cells is catalyzed when hormones outside the cell activate adenylyl cyclase. For 10 points - what is this primary second messenger of the body, a derivative of a purine ribonucleotide?
In slime mold amoebas, starvation induces secretion of this compound, causing the amoebas' walls to stick together end-to-end.
cyclic AMP or cAMP or cyclic 3'-5' adenosine monophosphate