Overall, the occurrence of such reactions suggests that GSH metabolism effected by GGT1 expressed at the surface of cancer cells can actually mediate sort of an extracellular detoxication of CDDP, which adds to the antioxidant defense offered by intracellular GSH against CDDP-induced oxidative stress, and is likely a major factor concurring to prevent its cytotoxicity (Figures 1A, D) (14–16). Here, GGT1 is linked to cancer.