Plasma LDL-C are cleared from the plasma mainly through the LDLR pathway. After LDLbinds toLDLR, LDL and LDLR are internalized into clathrincoated pits and degraded in the lysosome. Proproteinconvertase subtilisin/kexin type 9 (PCSK9) is a known secretory factor that negatively regulates theexpression level of LDLR on the cell membrane. PCSK9 mainly expressed in the liver tissues. SecretedPCSK9 binds to the LDLR and then increases lysosomal degradation. Studies on the human PCSK9genehave shown that PCSK9 gain-of-function mutations are related to familial hyperlipidemia, and PCSK9loss-of-function mutations have 15 to 28% lower LDL-C levels than ordinary people. Similarly, overexpression and knockout of PCSK9 in mice could down-regulate and up-regulate the expressionlevel of LDLR, respectively, resulting in hyperlipidemia and hypolipidemia in these two mice line. Therefore, PCSK9 is an important regulator in the cholesterol metabolism pathway. Inhibiting PCSK9 expressionlevel or activity could significantly reduce the level of "bad" cholesterol LDL-C. Thus, PCSK9is anefficient target for the development of anti-hyperlipidemia drugs. Gempharmatech has develop the B6-hPCSK9 mice which humanize the entire coding region of themouse PCSK9 gene. The liver LDLR expression level and plasma LDL-C level of this strain are similar tothose of wild-type mice. B6-hPCSK9 mice could develop hyperlipidemia through feedingwithhigh-cholesterol diet. Thus, B6-hPCSK9 mice is an ideal animal model for evaluating the efficacyof anti-hyperlipidemia drugs targeted PCSK9.