Western blot was performed using Anti-PKR Polyclonal Antibody (Product # PA5-20283) and a 60 kDa band corresponding to PKR was observed in all the tested cell models along with an uncharacterized band at ~250 kDa. Whole cell lysate (30 µg lysate) of HeLa (Lane 1), MCF-7 (Lane 2), HCT 116 (Lane 3), MDA-MB-231 (Lane 4), HT-29 (Lane 5), HL-60 (Lane 6) and Raji (Lane 7) were electrophoresed using Novex® NuPAGE® 4-12 % Bis-Tris gel (Product # NP0322BOX). Resolved proteins were then transferred onto a nitrocellulose membrane (Product # IB23001) by iBlot® 2 Dry Blotting System (Product # IB21001). The blot was probed with the primary antibody (1.5 µg/mL) and detected by chemiluminescence with Goat anti-Rabbit IgG (Heavy Chain), Superclonal™ Recombinant Secondary Antibody, HRP (Product # A27036, 1:4,000 dilution) using the iBright FL 1000 (Product # A32752). Chemiluminescent detection was performed using Novex® ECL Chemiluminescent Substrate Reagent Kit (Product # WP20005).