PCSK9 and atherosclerosis: Even though the liver is the major source, extrahepatic organs and cells (e.g., vascular smooth muscle cells (VSMC), vascular endothelial cells, and macrophages) can release PCSK9 [3], thus contributing, in a paracrine manner, to downregulate the local LDLR expression and eventually to promote the formation of foam cells and hence atherosclerosis progression [4].