. . . . . . "HIV-1 Tat causes a greater than 50% decrease in intracellular reduced glutathione (GSH), leading to the extracellular appearance of acidic FGF-1, an effect that is partially mediated through modulation of GSH biosynthetic enzymes" . "Expression of HIV-1 Tat in HeLa cells downregulates cytoplasmic glutathione peroxidase while upregulating phospholipid hydroperoxide glutathione peroxidase, thereby deregulating intracellular oxidant/antioxidant balance and amplifying UV sensitivity" . "downregulates" . "modulates" .