Glutathione is essential for energy metabolism in AML. (A) Complex II activity upon a 4-hour 125 nM cyst(e)inase treatment with or without a 2-hour pretreatment with 100 µM cell-permeable glutathione. Data normalized to no treatment control. (B) ATP levels on a 4-hour 125-nM cyst(e)inase treatment with or without a 2-hour pretreatment with 100 µM cell-permeable glutathione. Data normalized to no treatment control. (C) Western blot showing glutathione and succinate dehydrogenase A levels from succinate dehydrogenase A immunoprecipitation on a 4-hour 125-nM cyst(e)inase treatment with or without a 2-hour pretreatment with 100 µM cell-permeable glutathione. (D) Cell viability of ROS-low LSCs or ROS-high AML blasts pon increasing concentrations of cysteine depleting enzyme, cyst(e)inase. AML specimens 1 and 3 are sensitive to venetoclax with azacitidine, and AML specimens 2, 4, and 5 are resistant to venetoclax with azacitidine.²  (E) Viability of AML cells after a 24-hour 125-nM cyst(e)inase treatment with or without a 2-hour pretreatment with 100 µM cell-permeable glutathione. Data normalized to no treatment control. (F) Viability of CD34⁺ cells isolated from cord blood samples after a 24-hour 125 nM cyst(e)inase treatment. (G) Colony-forming number from CD34⁺ cells isolated from cord blood samples after a 24-hour, 125-nM cyst(e)inase treatment. (H) ATP level CD34⁺ cells isolated from cord blood samples after a 4-hour, 125-nM cyst(e)inase treatment. Statistical significance was determined by a 2-way analysis of variance analysis or Student’s t-test, where appropriate. *P < .05; **P < .01; ****P < .001.