Well, instead of using the protein kinase to actually reverse the reaction, we use a different enzyme known as protein phosphatases. So inside our body it's these protein phosphate phosphatases which are actually used to reverse the effects of the protein kinases. So protein kinases are responsible for phosphorylating that enzyme or the protein. But the protein phosphatases use a completely different reaction mechanism, a completely different reaction pathway to actually reverse the effect of the protein kinase and remove this phosphoryl group. And that can basically either activate or deactivate the activity of that enzyme. So if phosphorylation activates that enzyme, then defosphorylation will deactivate the activity of that enzyme.