In addition, leukemic cells exhibit adecline in reduced GSH and an increase in oxidized glutathione (GSSG)levels, indicating that AML cells are hypersensitive to chemotherapeuticdrug-mediated inhibition of GSH metabolism.4 Moreover, the mechanism underlying the development of cancer cellresistance to therapeutic drugs is based on the overexpression ofglutamate–cysteine ligase (GCL, GCLC) and glutathione synthetase(GSS) involved in GSH synthesis, leading to an increase in GSH/GSSG.8 Thus, it is important to measure the intracellularGSH/GSSG ratio in AML. Here, GSS is linked to cancer.