Modfit version 3.1

Cells were treated with BIBR1532 or exposed to radiation, or both. Annexin V-FITC and propidium iodide stains were used for apoptosis analysis. Cells were stained in the dark for 15 minutes at room temperature. For cell cycle analysis, cells were collected and fixed in 70% precooled ethanol overnight at 4 C. Cells were stained with a propidium iodideeRNase staining buffer at room temperature for 15 minutes and then analyzed using flow cytometry. Samples were analyzed using ModFit version 3.1 software (Verity Software House). For quantifying pHH3-positive cells, cells were fixed and permeated using eBioscience Foxp3/ Transcription Factor Staining Buffer Set (Thermo Fisher) for 1 hour in the dark at 4 C, incubated with pHH3 antibody (1:200), probed with the FITC-conjugated goat antirabbit secondary antibody (1:400; ZSGB-BIO, Beijing, China), and stained with a propidium iodideeRNase staining buffer. Each sample was then subjected to analyses with flow cytometry (BD FACSCanto II Flow Cytometer; BD Biosciences, Bedford, MA).