Furthermore, endothelial dysfunction and the following arterial stiffness have been related to the synergistic effect of smoking with inflammatory molecules of interleukin-6 (IL-6), C-reactive protein (CRP), and cyclooxygenase-1 and cyclooxygenase-2 (COX-1 and COX-2) [29, 30]. This evidence concerns the gene PTGS2 and endothelial dysfunction.