Representative Cr(V) signals from BEAS-2B cells exposed to 0.4 mM Na2CrO4 for 5 min at 37°C in LHC-9 medium under room air. Cells were grown in DMEM-HEPES medium with 10% FBS, harvested by scraping, washed in pre-warmed LHC-9 medium, and resuspended in a small volume of LHC-9 for incubation with Na2CrO4. Reactions contained 3 × 106 cells (A, B, C), or 5 × 106 cells (D). Prior to harvesting and washing in LHC-9, the cells in B were pretreated with 0.25 mM diamide for 30 min, and those in D with 0.1 mM PMS. For each, the total reaction volume was 0.25 ml and instrument settings were the same as in Fig. 1 except that the field set was 3480 G.