Now, cyclic Amp molecules are secondary messengers whereas the Glucagon hormones are primary messengers in this Glucagon signal transduction pathway. And so what cyclic Amp molecules do is they move on and bind onto the inactive version of PKA. So blue means inactive and red means active. Now, when cyclic and P bind onto the regulatory sides of PKA, they cause the dissociation of those regulatory sites from the catalytic sites from those catalytic subunits and that activates those catalytic subunits. So once this process takes place, that activates PKA protein kinase A. And remember that protein kinase A is capable of actually phosphorylating and thereby activating many other target proteins.