Potential origin and regulation of peroxiredoxin 4. Peroxiredoxin 4 (Prx4) is known to switch between dimer and pentadimeric decamer structure , with potential decameric structure having been identified in circulation . It has been shown that Prx4 redox-dependently binds to the cell surface of human umbilical vein endothelial cells . Specific and non-specific stimulation of various tissues has influenced Prx4 expression, oxidation or oligomerization and may ultimately result in secretion of Prx4. H2O2: hydrogen peroxide; LPS: lipopolysaccharide; NaDOC: sodium deoxycholate; NF-κB: nuclear factor-kappa B; NO: nitric oxide; Prx4: peroxiredoxin 4; RNS: reactive nitrogen species; TRAIL: tumor necrosis factor-related apoptosis-inducing ligand.