MMP9 and atherosclerosis: MMP‐9 is a 92‐kDa protein that belongs to a family of zinc‐ and calcium‐dependent endopeptidases (Fenhalls et al., 1999; Pourmotabbed et al., 1994) and plays a key role in all stages of atherosclerosis through monocyte recruitment influence, ECM degradation, endothelial cell migration, and activation of vascular smooth muscle cells (Blankenberg et al., 2003; Hirose et al., 2008; Ye, 2006).