EGLN1 and neoplasm: Strikingly, in comparison to OT-II-Th9 cells, succinate-treated OT-II-Th9 cells led to a greater reduction in the tumor volume (Fig. 7m), implying that succinate enhances the differentiation and anti-tumor functions of Th9 cells through increased stabilization of HIF1α by impairing PHD2 activity.