MMP12 is prominently expressed by aneurysm-infiltrating macrophages within the degenerating aortic media of patients with AAA [27, 51], as well as in the aortas from mice treated with CaCl2 or treated with Ang II and anti-transforming growth factor-β (TGF-β) antibody [26, 52]. This evidence concerns the gene MMP12 and aneurysm.