Western Blot Analysis of DNA Damage Response

Western blotting was performed as previously described [49 (link)]. Briefly, equal amounts of lysates were resolved with SDS-PAGE and were transferred onto PVDF membranes. Membranes were incubated with primary antibodies followed by horseradish peroxidase (HRP)-conjugated secondary antibodies. Signal amplification and detection were achieved by exposing the membrane to enhanced chemiluminescence reagent (GE Healthcare, Buckinghamshire, UK), followed by visualization using the Storm imaging system (Amersham Biosciences, Piscataway, NJ, USA). The following primary antibodies were used: γ-H2AX (1/1000; Cell Signaling Technology, Beverly, MA, USA), Chk2 (1/500; Cell Signaling Technology), Phospho-Chk2 (Thr68) (1/1000; Cell Signaling Technology), XRCC2 (1:1500; Abcam), Caspase-9 (1/500; Proteintech, Chicago, IL, USA), Caspase-3 (1/500; Proteintech), PARP (1/500; Proteintech), and BCL-2 (1/500; Santa Cruz Biotechnology). Detection of GADPH (1/10000; Cell Signaling Technology) was used as a loading control. Bound antibodies were visualized with peroxidase-linked secondary antibodies (anti-rabbit antibody: 1/10000; Cell Signaling Technology and anti-mouse antibody: 1/5000; Sigma-Aldrich, St. Louis, MO, USA).