Effect of Tempol on cell killing induced by chemotherapy drugs in the presence and absence of H₂O₂.

Cells were treated for 18 hours with 1.7 μmol/L VP-16 or 50 μmol/L cisplatin in the presence or absence of 75 μmol/L H₂O₂ and 0.5 mmol/L Tempol and analyzed as described in the legend to Figure 2. The order of addition of reagents was Tempol first, followed by chemotherapy drug, followed by H₂O₂ (30-minute delay). Pyknotic/necrotic cells are indicated by ▪, and apoptopic cells are indicated by □.