APOE and atherosclerosis: Role of mast cells in the progression of atherosclerosis has been further confirmed by findings that mast cell deficiency attenuated the development of atherosclerotic plaque in both LDL receptor-deficient LDLr−/− /KitW-sh/W−/sh mouse model (87) and apoE-deficient apoE−/−/KitW-sh/W−/sh mouse model (436).