And notice that unlike the insulin case where a single insulin binds to the insulin receptor in this case two EGF molecules actually bind to this EGF receptor. One binds on this side and the other binds on this opposing side. Now, upon the binding of these two EGF molecules onto these extracellular domains what happens is there is a section on this side and this side of these two domains that we call the dimerization arm. And upon the binding, each one of these dimerization arms basically stretches out and reaches out into a pocket found on the posing domain. So this arm stretches and binds here and this arm stretches and binds here. Because upon the binding of the EGF, there is a conformational change that takes place that allows these two intersurfaces to basically interact with one another.