PCSK9 and atherosclerosis: In this study, we induced atherosclerosis in Stk25 knockout and transgenic mice, and their wild-type littermates, by gene transfer of gain-of-function mutant of proprotein convertase subtilisin/kexin type 9 (PCSK9), which induces the downregulation of hepatic low-density lipoprotein receptor (LDLR), combined with a western-type diet.