FIGURE 6.

Resistance to oxidative cell injury in senescent cells. A, role of ERK1/2 in oxidative stress-induced cell injury. NRK cells were exposed to 100 μm H₂O₂ (left panel) or 50 μm menadione (Mena, right panel) in the presence or absence of 50 μm PD98059 for 12 h. The cell morphology under phase-contrast microscopy was photographed (magnification, ×200). B–D, resistance to oxidative injury in senescent cells. Cells were treated with or without 1 μg/ml ETO for 3 days, and then cells were exposed to 100 μm H₂O₂ for 12 h and subjected to phase-contrast microscopy (B) or formazan assay (D). The quantitative result of B is shown in C. Results are expressed as mean ± S.E. (n = 4). *, p < 0.05 versus untreated control.