RBP4 and systemic lupus erythematosus: Inflammation and cytokines represent a cornerstone in the etiopathogenesis of SLE; IL-6, retinol-binding protein 4 (RBP4), tumor necrosis factor α (TNF-α), IFN-α, and B-lymphocyte stimulator (BLyS) have all been detected in lupus as in the study done by Solano et al.