MMP9 and triple-A syndrome: An important MMP regulator found in human AAA tissue is the activator of MMP‐2, called membrane type 1 MMP (MT‐1 MMP).75, 80, 86 In TAA and TAD tissue, increased levels of MMP‐1, MMP‐2 and MMP‐9 expression by vSMC compared with control are reported.62, 87, 88, 89, 90, 91 MMP‐2 has a dual role in ECM turnover in the mouse thoracic aorta: it mediates ECM degradation, as well as ECM synthesis.92