In contrast, the expressions of tissue inhibitor of metalloproteinase 1 (TIMP1) and TIMP2, which are endogenous inhibitors for MMPs, were markedly reduced in cultured VSMCs and aorta of RhoA cKO mice (Supplementary Fig. 5f–j), suggesting that both increased MMPs expression and their enhanced activity from reduced expression of TIMPs cooperatively contribute to the robust degradation of ECM for AAA formation in the aorta of RhoA cKO mice. Here, TIMP2 is linked to triple-A syndrome.