EPAS1 and breast cancer: In hepatocellular carcinoma, glutaminase 1 enhances stemness by reducing ROS.[26] Conversely, in breast cancer, lowering ROS levels diminishes cancer cell stemness by downregulating HIF2α.[27] These results suggest that ROS can either promote or inhibit cancer cell stemness by disrupting intracellular ROS homeostasis or triggering different cascade signaling responses.