IL20 and rheumatoid arthritis: Previous researchers have focused on the ability of IL-20 to act as a proinflammatory, chemotactic, and angiogenic cytokine in skin inflammation diseases [24], RA [16], liver fibrosis [14] and ischemic diseases [25] by activating its heterodimeric receptors (either IL-20RA/IL-20RB or IL-22RA1/IL-20RB).