Immunofluorescent double staining showed reduced lesion Ki67+α‐actin+ double‐positive proliferating SMCs but increased caspase‐3+α‐actin+ apoptotic SMCs in AAA lesions from Rorafl/flIl7rCre/+ mice (Figure 2H/I), suggesting that the loss of medial SMCs in these mice results from less SMC proliferation and increased SMC apoptosis. This evidence concerns the gene MKI67 and triple-A syndrome.