Mice with infrarenal abdominal aortic aneurysm were used to identify four subpopulations of SMCs: quiescent-contractile SMCs (Myh11+, Acta2+, Tagln+, Myl9+), proliferative-contractile SMCs (Fos+, Jun+, Klf2+, Atf3+, Dusp1+), dedifferentiated SMCs (Ifrd1+, Klf4+, Atf3+, Klf2+, Ctss+, Adamts1+, Cxcl2+, Ccl2+, Mt1+, Mt2+, Hk2+, Gata6+), and inflammatory SMCs (Ifrd1+, Nrip2+, Pln+, Klf4+, Atf3+, Klf2+, Ctss+, Adamts1+, Cxcl2+, Ccl2+, Sparcl1+, Igfbp5+, Sncg+, Thbs1+, Notch3+)11. The gene discussed is CTSS; the disease is abdominal aortic aneurysm.