the serum lipoproteins were fractionated by density gradient ultracentrifugation into very low density lipoproteins ( vldl ) , low density lipoproteins ( ldl ) , and into the high density lipoprotein ( hdl ) subfractions 2 and 3 ( hdl2 , hdl3 ) .
C0023820
lipoproteins
C0023825
very low density lipoproteins