Figure 2.

The RIR motif is important for XRCC1-dependent cell survival following oxidative stress. A, clonogenic survival of XRCC1-mutant EM9 cells stably transfected with empty pCD2E vector (V) or with pCD2E expression constructs encoding full-length wild-type XRCC1-His (EM9-XH) or XRCC1-His^FFF (EM9-XH^FFF). Cells were treated with the indicated concentrations of H₂O₂ for 15 min and then in drug-free medium for 10–14 days to allow colony formation. Data are the mean ± S.E. of three independent experiments. Where not visible, error bars are smaller than the symbols. B, clonogenic cell survival following MMS treatment, as above.