High-density lipoproteins (HDL), also known as "good cholesterol," remove excess cholesterol from the body's tissues and transport it to the liver. This process is known to prevent atherosclerosis, the build-up of plaque in the walls of arteries. Atherosclerosis is associated with deadly symptoms, including heart attacks, strokes, aneurysms, and blood clots. Despite the importance of HDLs, scientists still have a limited understanding of how they are made.