These findings have (i) identified MIF expression in the brain, particularly in areas significant to the behavioral symptoms of depression; (ii) established the significance of the hypothalamic-pituitary-adrenal (HPA) axis in depression, with which MIF has an intricate relationship; (iii) shown an interaction between MIF and both lifestyle and pharmacological antidepressant treatments; (iv) determined a connection between MIF and neurogenesis, another important avenue of depression research; and (v) explored MIF as a biomarker in major depression and other mood disorders. The gene discussed is MIF; the disease is major depressive disorder.