Now in its unbound state. Before the EGF molecules bind onto this receptor we see that the EGF receptor actually consists of two identical but separated monomeric units. So this is monomer number one and this is monomer number two. And these two monomers are not attached by any type of bond so they're actually separated. And as we'll see in just a moment they actually dimerize. They form a dimer only upon the binding of the EGF molecule.