Macrophage migration inhibitory factor (MIF), widely expressed in monocytes, macrophages and T-cells [10], is an upstream immunoregulatory cytokine that contributes to the pathogenesis of many acute and chronic inflammatory diseases such as septic shock [11], rheumatoid arthritis [12] and systemic lupus erythematosus [13]. The gene discussed is MIF; the disease is rheumatoid arthritis.