HTN has been associated with increased levels of matrix metalloproteinase-9 (MMP-9) [49,50] and since SDC4 is a target of MMP-9 [51], HTN leads to the overexpression of MMP-9 to an increased amount of SDC4 shedding, releasing the ectodomain of SDC4 to the circulation and thereby potentially reducing the amount of SDC4 on the endothelial surface, which is suggested to reduce eNOS activity [52]. Here, MMP9 is linked to hypertensive disorder.