To determine whether the activities of proteasome are altered during AAA formation and progression, we collected abdominal aortas in Apo E−/− mice on the 14th (2w-Ang II) and 28th (4w-Ang II) day in Apo E−/− mice after saline or Ang II infusion and measured 20S proteasome peptidase activities. Here, APOE is linked to triple-A syndrome.