So we basically have these two identical monomers in their unbound form. They're separated because the EGF is not bound to this structure. But let's see what happens upon the binding of EGF. 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.