Overexpression of HDAC1 or HDAC2 in NEDP1 KO cells can rescue the induction of PAR polymer following H2O2 treatment. U2OS WT or NEDP1 KO cells were transfected with the indicated FLAG vectors. 48 post-transfection cells, were treated with H2O2 (600 μM) for the indicated amount of time and harvested directly in sample loading buffer. Lysates were resolved by SDS-PAGE and processed for Western blot analysis with the indicated antibodies. 