APOE and triple-A syndrome: To further validate the role of DKK3 in VSMCs during AAA development, we utilized AAV2/9 vectors carrying short hairpin RNA (shRNA)–DKK3 with an SM22α promoter (pHBAAV2/9-SM22a-mir30-m-DKK3) to specifically knock down DKK3 in VSMCs in Ang II-induced Dkk3+/+Apoe−/− mice.