To more fully examine the impact of TNF-α signaling, ER stress activation, and VSMC dysfunction during AAA development, murine aortic VSMCs were isolated and stimulated with TNF-α which resulted in significant upregulation and activation of phosphorylated eIF2a, Atf4, and Chop at both the RNA and protein level (Figure 2, A–C). Here, ATF4 is linked to triple-A syndrome.