TGFB1 and aortic aneurysm: The conclusion that baseline TGFβ signaling is protective against aortic aneurysm is supported by mouse studies, in which homozygous deletions of TGFBRI or TGFBRII in aortic smooth muscle have been reported to be sufficient for initiating TAAs (Choudhary et al., 2009; Hu et al., 2015; Li et al., 2014; Schmit et al., 2015).