Many above-mentioned signaling pathway proteins, including tumor necrosis factor, interleukins IL-1, IL-6, and IL-8, nuclear factor κB (NF-κB), the renin–angiotensin system, and hypoxia-inducible factor-1 (HIF-1) participate in the molecular mechanisms underlying the OSAS-induced endothelial dysfunction (4,145). Here, REN is linked to endothelial dysfunction.