The upregulation of TGF-β1 and ERK1/2 signaling may also account for the observed proliferation in the vessel wall38 (Fig. 1, Supplemental Fig. S3).These studies emphasize the complexity of TGF-β signaling pathways in the pathogenesis of aortic aneurysms. The gene discussed is TGFB1; the disease is aortic aneurysm.