G6PD and neoplasm: To investigate the roles of FOXO1 and G6PD in tumor growth at high ROS levels in vivo, we injected control and G6PD-overexpressing MDA-MB-231 cells, with or without FOXO1 knockdown, into immunocompromised mice and treated with H2O2 (200 μM) via intratumoral injection every week from Week 2 to Week 4.