Well, because the brain cells depend on glucose molecules. And the brain cells are arguably some of the most important cells in our body. And they need to get that glucose first before any other cell actually gets the glucose. And so that's why they have a high concentration of the glute three, because this has a Km value around one. That makes it very, very effective in binding that glucose and bringing that glucose into the cytoplasm of the nerve cells. Now let's move on to glute three, glute four and glute five.