MMP9 and triple-A syndrome: Wang et al. (2012) found that AMP-activated protein kinase α2 showed increased nuclear co-localization with nicotine, upregulating MMP expression, and instigating the formation of AAA in genetically modified mice. Our data are in line with these findings, as they show upregulated aortic expression and activity of MMP-2 and MMP-9 with prolonged nicotine exposure, and are also consistent with other reports showing similar findings in vascular cells, such as endothelial cells and SMCs (Carty et al., 1996; Jacob-Ferreira et al., 2010; Dom et al., 2011).