Representative 2D electrophoresis of oxidized protein thiols in untreated (left) vs. Cr(VI)-treated (25 µM, 90 min) (right) BEAS-2B cells. M = marker lane at left of each gel. An expanded view of the regions containing Trx and Prx are shown at the bottom. Increased fluorescence following Cr(VI) treatment of the cells indicates greater oxidation of that protein (the 6 circled spots). After image capture, the gels were transferred to nitrocellulose and sequentially probed with different antibodies. Spots 4, 5, and 6 exactly correspond to the positions of Prx3, Trx1, and Trx2, respectively. Spots 1–3 have are have not been identified.