The transporter protein ABCA1 (shown in red) is important in many lipid disorders and diabetes. Normally, it pumps cholesterol out of the cell as HDL, the good form of cholesterol in the bloodstream. The first part of this animation shows ABCA1 working in pancreatic islet cells, the cells that secrete insulin. While ABCA1 is working, insulin (the purple protein) is secreted normally. However, in the second part, when ABCA1 is not working, cholesterol builds up in the cell, influencing membrane fluidity and severely limiting the secretion of insulin.