So, we have the phospholipid bilayer of the red blood cell. This is our cytoplasm portion, and this is the extracellular matrix. So this is the protein component of the glycoprotein. And these purple extensions are the sugar components. And it's the terminal sugar of that glycoprotein that determines the type of blood type or blood group that our individual has. Now, these glycoproteins are also sometimes known as self antigens or simply antigens, as we'll see in just a moment.