Western blot was performed using Anti-Calprotectin Monoclonal Antibody (MAC387) (Product # MA5-16808) and a 13kDa band corresponding to Calprotectin was observed in SK-BR-3 and THP-1 but was absent in Raji and SH-SY5Y which are reported to be negative. Expression of Calprotectin was downregulated upon treatment of THP-1 with PMA/TPA [10.1073/pnas.0709958105]. Membrane enriched cell extracts (30 µg lysate) of SK-BR-3 (Lane 1), THP-1 (Lane 2), THP-1 treated with PMA/TPA (50ng/ml for 24 hours) (Lane 3), Raji (Lane 4) and SH-SY5Y (Lane 5) 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 (1:1000 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).