So whenever you hear the word mutase, what that should basically tell you is you're dealing with some type of enzyme that catalyzes a reaction in which it moves some type of group from one point on the molecule to a different point on that molecule. And so in this particular case, the mutase is a phosphoglycerate mutase. It moves a phosphoryl group within this phosphorylycerate molecule. So in this step, an enzyme called phosphoglycerate mutase catalyzes the movement of a phosphoryl group from the third carbon on this three phosphaglycerate onto the second carbon of that same molecule. And so this is what we form. Now, this is the net overall reaction.