Macrophage migration inhibitory factor (MIF or MMIF), also known as glycosylation-inhibiting factor (GIF), L-dopachrome isomerase, or phenylpyruvate tautomerase is a protein that in humans is encoded by the MIF gene. MIF is an important regulator of innate immunity. The MIF protein superfamily also includes a second member with functionally related properties, the D-dopachrome tautomerase (D-DT). Bacterial antigens stimulate white blood cells to release MIF into the blood stream. The circulating MIF binds to CD74 on other immune cells to trigger an acute immune response. Hence, MIF is classified as an inflammatory cytokine. Furthermore, glucocorticoids also stimulate white blood cells to release MIF and hence MIF partially counteracts the inhibitory effects that glucocorticoids have on the immune system. Finally trauma activates the anterior pituitary gland to release MIF.