2.6. Western blot analysis of poly (ADP-ribose) polymerase (PARP) expression

The cellular lysate was prepared using ice-cold lysis buffer consisting of 1% NP40, 1 mM DTT and protease inhibitors in PBS. The protein concentration was quantified through Bradford assays (Bio-Rad Laboratories, USA). Protein (50 μg) from each sample was subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting as described previously (Soo et al., 2017). Primary antibodies targeting PARP at 1: 1000 (Cell Signalling Technology, USA) and β-actin at 1: 1000 (Santa Cruz Biotechnology, USA) were incubated on polyvinylidene difluoride (PVDF) membrane overnight. Following 3 times washing with PBST consisting of 1× PBS and 0.1% Tween-20, the blots were incubated with diluted enzyme-linked secondary antibodies. The detection of specific antibodies was carried out with Enhance Chemiluminescence (ECL)™ Select Western Blotting Detection Reagent (Sigma-Aldrich, USA). The images were captured using the ChemiDoc™ XRS + System (Bio-Rad Laboratories, USA).