(a) Oxidized glutathione levels in dermal fibroblasts were increased at 72 h when the cells were exposed to 4 or 8 Gy IR. This increase was prevented when cells received 5 μM TRFRB 24 h before IR. Each data point represents mean ± SD of treatment dishes. as compared to sham DMSO group, as compared to IR treated group. (b) There was no significant change in these cells that received TRFRB for the cell cycle reentry in 24 h following 2, 4, 6, or 8 Gy irradiation.