AGT and triple-A syndrome: To test for cell proliferation in AngII AAA, we stained fixed supra-renal abdominal aortic tissue from ApoE−/− mice infused with saline or AngII for 28 days with Ki67, which accumulates in cells throughout the S, G2, and M cell cycle phases.21 A significant increase in the proportion of Ki67-positive nuclei was observed in the aortic wall in AngII-infused mice compared to saline controls (P < 0.001, Figure 1B to C), and this was positively correlated with aortic volume (Figure 1D).