Fig. (5) Reductide uptake and reduction is inhibited by glutathione depletion.BJ fibroblasts were seeded into a 96-well plate at a density of 4,000 cells per well and allowed to attach overnight. The following day, cells were treated with (A) the glutathione biosynthesis inhibitor l-buthionine sulfoximine (BSO) or (B) the thiol oxidizing agent diamide in normal media also containing reductide 1 µM.