As further direct support for an extracellular role for GrB in disease, we have recently shown that GrB contributes to murine abdominal aortic aneurysm (AAA) pathogenesis through the cleavage of extracellular matrix (ECM) proteins such as fibrillin-1 and decorin [8], [9]. The gene discussed is GZMB; the disease is abdominal aortic aneurysm.