You are interested in cell size regulation and discover that signaling through a GPCR is important in controlling cell size in rat white blood cells. The G protein downstream of this receptor activates adenylyl cyclase, which ultimately leads to the activation of PKA. You find that cells that lack the GPCR are 15% smaller than normal cells, whereas cells that express a mutant, constitutively activated version of PKA are 15% larger than normal cells. Furthermore, the normal blood cells become smaller when treated with cholera toxin, which has been shown to inhibit certain subclasses of the a subunit of the G protein. Given these results, explain what you predict would happen to the cell's size (bigger, smaller, or no change) if cells were treated in the following fashion

A. You add pertussis toxin
B. You inhibit the RGS protein that normally works on the a subunit of the G protein involved in this pathway.
C. You add a drug that increases the activity of cyclic AMP phosphodiesterase
D. You add a drug that inhibits adenylyl cyclase.
E. You mutate the cAMP-binding sites in the regulatory subunits of PKA, so that the PKA binds more tightly to cAMP.