Flow cytometry-based apoptosis assay

Human breast cancer cell lines CAL-51 and MCF-7 were treated for 48 h with DMSO vehicle, 10 μM KU55933, 10 μM Olaparib, or the combination of 10 μM Olaparib and 10 μM KU55933. Cells were harvested by trypsinization, resuspended to a density of 1 × 10⁶ cells/mL in 1 × binding buffer, and stained with FITC-Annexin V and propidium iodide (PI) using the FITC Annexin V Apoptosis Detection Kit I (BD Biosciences). Stained cells were analyzed using an LSRII flow cytometer (Falcon BD, San Jose, CA, United States) according to the manufacturer’s instructions. All experiments were performed in triplicate.