Sort the following events to reflect the normal order in which they occur in G-protein-coupled receptor signaling leading to transcription of genes with cAMP response elements. Your answer would be a four-letter string composed of letters A to E only, e.g. ACBD. a. Binding of CREB to PKA b. Binding of cAMP to PKA c. Dissociation of PKA into catalytic and regulatory subunits d. Activation of adenylyl cyclase