So in liver cells that's our goal is to actually regulate the concentration of glucose inside our blood. So our liver is responsible for regulating the concentration of glucose in the blood. And what that means is liver cells can actually mobilize glycogen by breaking down to glucose, but they don't actually use that glucose to form ATP. Instead, they can release that glucose into the blood to basically increase the concentration of glucose in the blood when the blood glucose levels drop below normal. Now, how exactly is glycogen breakdown controlled in the liver? So in the liver, we also regulate the breakdown of glycogen by regulating the allosteric enzyme we call glycogen phosphorylase.