Western blot was performed using Anti-Histone H4 Recombinant Rabbit Monoclonal Antibody (SD209-04) (Product # MA5-32370) and an 11kDa band corresponding to Histone H4 was observed across the cell lines tested. Acid extracts (15 µg lysate) of SK-O-V3 (Lane 1), Raji (Lane 2), HEK-293 (Lane 3) and HeLa (Lane 4) were electrophoresed using NuPAGE™ 4-12% Bis-Tris Protein Gel (Product # NP0321BOX). Resolved proteins were then transferred onto a nitrocellulose membrane (Product # IB24001) by iBlot® 2 Dry Blotting System (Product # IB21001). The blot was probed with the primary antibody at 1:1000 dilution and detected by chemiluminescence with Goat anti-Rabbit IgG (Heavy Chain) Superclonal™ Recombinant Secondary Antibody, HRP (Product # A27036,1:4000 dilution) using the iBright™ FL1500 Imaging System (Product # A44115). Chemiluminescent detection was performed using Novex® ECL Chemiluminescent Substrate Reagent Kit (Product # WP20005).