In addition to the cytokines and chemokines that are generally associated with inflamed RA joints (such as IL-1RA, IL-6 or IL-18), we also identified proteins including macrophage migration inhibitory factor (MIF), plasminogen activator inhibitor 1 (PAI-1), and soluble ICAM-1 (sICAM-1) that are not extensively discussed but are also implicated in the RA pathogenesis [24,25,26]. Here, SERPINE1 is linked to rheumatoid arthritis.