So the entire point of these regions is to basically allow the attachment of other important proteins that are part of the EGF signal transduction pathway. And to see what we mean by that, let's take a look at the following diagram. So we can see that there are many different types of proteins and enzymes involved in this process. And so I've labeled 123-4567. So let's basically see what each one of these steps actually involves. And let's begin with step number one.