Figure 6. Prolonged H2AX phosphorylation induced by brief H₂O₂ exposure in Ppm1d^−/− MEFs. Wt and Ppm1d^−/− MEFs at passage 1 cultured in 3% O₂ were treated with 100 µM H₂O₂ for 15 min. Cells were then washed with PBS and incubated in fresh complete medium. Cells were collected at indicated times (0.5, 8, and 24 h) after H₂O₂ treatment, and blotted proteins were probed with Wip1, γH2AX and β-actin antibodies. β-actin was used as loading control. NT, no treatment. The data are representative of 3 independent experiments.