APOE and atherosclerosis: In Western diet (WD)-fed Sphk1−/− mice and Sphk2−/− mice, both with an ApoE-deficient background, the exacerbation of atherosclerosis in mice lacking Sphk2, but not Sphk1, was attributed to impaired autophagic degradation of lipid droplets (LDs) in macrophages [174].