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. And in this particular stigma transduction pathway, the target protein is phosphorolase kinase. So remember from a previous discussion that phosphorase kinase must be activated by two different factors. One is phosphorylation and the other one is calcium.