Western blotting was performed as described previously.25 (link) Briefly, proteins were transferred to nitrocellulose membrane using a Trans-Blot Turbo Transfer System (BioRad, Montreal, QC, Canada), transfer was confirmed using Ponceau S stain (0.1% (w/v) in 5% (v/v) acetic acid) and the membranes were blocked in 5% skim milk in Tris-buffered saline with 0.1% (v/v) Tween-20 (TBS-T; 50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 0.1% (v/v) Tween-20) at room temperature for 2 hours. The membranes were incubated overnight at 4°C with the following primary antibodies diluted in 5% (w/v) skim milk in TBS-T: anti-poly-(ADP- ribose) polymerase (PARP) (1:3,000, 9542S; Cell Signaling Technology, Whitby, ON, Canada), anti-caspase 3 (1:500, 9662S; Cell Signaling Technology), anti-caspase 7 (1:1,000, 9492S; Cell Signaling Technology), anti-caspase 9 (1:1,000, 9502S; Cell Signaling Technology), and anti-β-actin (1:5,000, 8457L; Cell Signaling Technology). Membranes were washed three times with TBS-T, incubated with anti- rabbit secondary antibody (1:3,000, 7074S, Cell Signaling Technology), washed three times with TBS-T, incubated with Western Lightning Plus-ECL reagent (PerkinElmer Inc., Waltham, MA, USA) for 2 minutes, and developed using the chemiluminescence setting on a ChemiDoc MP Imaging System (BioRad).