An example of a uniporter is the glucose transporter (GLUT) in found in erythrocytes (referred to as GLUT1 to separate from other mammalian glucose transporters). This allows glucose to enter the cell via facilitated diffusion and it does so at approximately 50,000 times the rate that it would via simple diffusion. This process is not active (meaning it does not require an energy input). Once inside the cell the glucose is quickly phosphorylated to glucose-6-phosphate by the enzyme, hexokinase, to prevent it from diffusing out. This is also the first step in glycolysis.