Macrophage migration inhibitory factor (MIF or MMIF), also known as glycosylation-inhibiting factor (GIF), L-dopachrome isomerase, or phenylpyruvate tautomerase is an important regulator of innate immunity. It is involved in cell-mediated immunity, immunoregulation, and inflammation. MIF plays a role in the regulation of macrophage function in host defense through the suppression of anti-inflammatory effects of glucocorticoids. This lymphokine and the JAB1 protein form a complex in the cytosol near the peripheral plasma membrane, which may indicate a role in integrin signaling pathways. MIF is an inflammatory mediator associated with rheumatoid arthritis (RA) severity. It has also been shown to induce changes in the heart during sepsis. Additionally, evidence suggests that there is a correlation between MIF production and metastatic potential in colorectal cancer.