EDN1 and endothelial dysfunction: However, when furin activity is increased via ET-1 released from the endothelium, this not only assures a homeostatic regulation of pro-MMP2 activity in the arterial wall under physiological conditions but, under conditions of endothelial dysfunction, stimulates, in the presence of ANGII, the activation of latent pro-MMP2 via the ET-1/ETA/Furin pathway.