We exploited a noninvasive biosensor (Grx1-roGFP2) (roGFP, reduction-oxidation-sensitive green fluorescent protein) of GSH redox potential (EGSH) (24) to measure dynamic changes in the redox physiology of human macrophages (U937) upon infection with a virulent strain of M. tuberculosis (H37Rv). This evidence concerns the gene GLRX and infection.