Fig. 4.

A, protein levels of PRX1 (expressed relative to the HPL1D cell line used as an internal control) correlated negatively with intracellular ROS/RNS level measured as DCF fluorescence (arbitrary units). JS-K toxicity measured as IC₅₀ values correlated with levels of PRX1. B, silencing of peroxiredoxins with a pool of siRNAs sensitized the cells to JS-K. H1703 cells were treated with a siRNA pool for all six isoforms of PRX for 48 h in complete medium followed by 0.5 μM JS-K for 24 h. Percentage of dead cells was measured by the trypan blue exclusion method. Loss of PRX-1 signal after siRNA treatment was shown by Western blot. M, mock control; si, siRNA to PRX pool; NS, nonsilencing siRNA negative control.