Cell cycle analysis by flow cytometry

Cells were incubated with or without 1 μM olaparib for 24 hours. Cells were then collected and fixed with 70% EtOH for 30 min on ice. Cells were washed with PBS and treated with ribonuclease A solution (10 μg/ml; Sigma-Aldrich) for 20 min at RT. DNA content of the cells were stained with propidium iodide solution [0.1% Triton X-100 and propidium iodide (500 μg/ml); Sigma-Aldrich] for 10 min. G₀-G₁, S phase, and G₂-M were differentiated by a flow cytometer (BD FACSCalibur), using BD CellQuest Pro version 6.0, ModFit LT software.