Well, basically specific types of hormones. So we have hormones such as glucagon and epinephrine that can initiate the breakdown of the mobilization of triglycerides. So we have some type of primary messenger molecule. So it can be glucagon or it can be epinephrine that binds onto a specific seven transmembrane protein receptor found on the membrane of adipose cells. And once it actually binds, it creates a conformational change in that seven TM structure and that causes structural changes in the g protein. And what that does is it releases the GDP and it basically accepts the GTP.