8- (2- Aminoethylthio)- 2'-O- methyladenosine- 3', 5'- cyclic monophosphate, immobilized on agarose gel (8-AET-2'-O-Me-cAMP-Agarose)[8- (2- Aminoethylthio)- 2'-O- methyladenosine- 3', 5'- cyclic monophosphate, immobilized on agarose gel (8-AET-2'-O-Me-cAMP-Agarose)]