Figure 2: The cellular cholesterol partition and key enzymes of cholesterol metabolism. The cholesterol (C) from low-density lipoprotein (LDL) could be uptaken by liver cell via two ways, the endocytosis and hydrolyze LDL via lysosome or digest and uptake via lipoprotein lipase on the cell membrane. Cholesterol could be esterified into cholesteryl esters (CE) for storage in liver or be used for synthesize bile acid or oxysterol via cholesterol 7 alpha-hydroxylase (CYP7A1) on endoplasmic reticulum (ER) or via sterol 27-hydroxylase (CYP27A) in mitochondria. Cholesterol could also be synthesized de novo via enzyme on ER.