Flow cytometric analysis of cell cycle distribution

After appropriate treatment, cells were washed twice with ice‐cold phosphate‐buffered saline (PBS), harvested, and fixed in cool 70% ethanol at 4 °C overnight. After fixation, cells were incubated with 50 mg·mL⁻¹ PI staining solution with RNase A for 30 min at room temperature. The distribution of different DNA contents was analyzed by a FACScan flow cytometer (Becton Dickinson).