APOE and triple-A syndrome: Similarly, we generated vascular smooth muscle cell (VSMC)-specific COMP transgenic (COMPSM-Tg) ApoE–/– mice, as aortic COMP is mainly derived from VSMCs in the vessels.37 A 28-day AngII infusion caused > 50% (7/12) of the ApoE–/– mice to develop AAA.