<prompt> Answer this question truthfullyWhat is the effect of increased glucagon levels during fasting on the activity of FBPase-2 and PFK-2, and what is the mechanism behind it?  <response>: <reason> Increased glucagon levels during fasting lead to increased cAMP and protein kinase A, which in turn increase the activity of FBPase-2 and decrease the activity of PFK-2. 