PCSK9 (also known as neural apoptosisregulated convertase, NARC-1) is a 692-residue extracellular protein expressed primarily in the kidneys, liver and intestine representing the 9th member of the secretory subtilase family. The secreted form of PCSK9 binds directly to the LDLR and results in degradation of the receptor. Medicines for hypercholesterolemia including statin are reported to increase the level of circulating PCSK9. This suggests the possibility that inhibition or decrease of PCSK9 may potentiate the drug efficacy while administration of hypercholesterolemia drugs at low concentration. Being a target for therapeutic drugs under development, PCSK9 is now a popular research target.