Two recent studies [86, 87] also demonstrated that glucocorticoid-induced TNF receptor-related protein (GITR) ligation directs the differentiation of iTreg cells into TH9 cells and thus mediates anti-tumor immunity, indicating that reciprocal differentiation of T cell lineages is critical for the anti-tumor effects of TH9 cells. The gene discussed is TNFRSF18; the disease is neoplasm.