PCSK9 and hyperlipidemia: Ddr1WT (Ddr1flox/flox, Cdh5-CreERT2−) and Ddr1iECKO mice were injected once with adeno-associated-virus-8 (AAV8)-overexpressing PCSK9 (AAV8-PCSK9) via the tail vein and fed on a Western diet to induce hyperlipidemia, a potent risk factor for atherosclerosis.