It allows the attachment of an important protein shown in two, that is known as the SOS protein. So in one we have the phosphorylated region of the EGF receptor. This section here acts as an anchor for and adapt the protein we call GRB Two. Next, what this GRB Two does is it allows the attachment of the SOS protein. So GRB Two recruits another protein called SOS, shown in dark purple. And what the SOS does is it contains an active side that basically binds.