Immunohistochemistry with anti-PARP-1 antibody showing nuclear positivity in human lung tissue at 20x and 40x (B & C). Staining was performed on Leica Bond system using the standard protocol. Formalin fixed/paraffin embedded tissue sections were subjected to antigen retrieval and then incubated with rabbit anti-PARP-1 antibody 200-401-GM8 at 1:100 dilution for 60 minutes. Biotinylated Anti-rabbit secondary antibody was used at 1:200 dilution to detect primary antibody. The reaction was developed using streptavidin-HRP conjugated compact polymer system and visualized with chromogen substrate, 3’3-diamino-benzidine substrate (DAB). The sections were then counterstained with hematoxylin to detect cell nuclei.