Western blot was performed using Anti-Chk1 Monoclonal Antibody (2G1D5) (Product # MA5-15239) and a 55kDa band corresponding to Chk1 was observed across cell lines tested. Whole cell extracts (30µg lysate) of HeLa (Lane 1), SH-SY5Y (Lane 2), HCT 116 (Lane 3), A549 (Lane 4) and K-562 (Lane 5) were electrophoresed using NuPAGE™ 4-12% Bis-Tris Protein Gel (Product # NP0321BOX). 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 (1:1000 dilution) and detected by chemiluminescence with Goat anti-Mouse IgG (H+L) Superclonal™ Recombinant Secondary Antibody, HRP (Product # A28177, 1:4000 dilution) using the iBright FL 1000 (Product # A32752). Chemiluminescent detection was performed using Novex® ECL Chemiluminescent Substrate Reagent Kit (Product # WP20005).