PCSK9 and hyperlipidemia: E3L mice are prone to develop hyperlipidemia and atherosclerosis upon feeding a Western-type diet containing saturated fat and cholesterol [13], and they respond similarly as humans do to lipid-modulating interventions that are being used in the clinic (e.g., statins, fibrates, niacin, and PCSK9 inhibitors) [11, 14–22].