Western blot was performed using Anti-Neutrophil elastase Recombinant Rabbit Monoclonal Antibody (JF098-6) (Product # MA5-32548) and a 29kDa band corresponding to Neutrophil elastase was observed in HL-60, U-937, THP-1 but not in HEk-293, MDA-MB-231 and A549 which are reported to be negative. Whole cell extracts of HL-60 (Lane 1), U-937 (Lane 2), THP-1 (Lane 3), HEK-293 (Lane 4), MDA-MB-231 (Lane 5) and A549 (Lane 6) were electrophoresed using NuPAGE™ 12% Bis-Tris Protein Gel (Product # NP0341BOX). 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-Rabbit IgG (Heavy Chain), Superclonal™ Recombinant Secondary Antibody, HRP (Product # A27036, 1:4000 dilution) using the iBright FL 1000 (Product # A32752). Chemiluminescent detection was performed using Novex® ECL Chemiluminescent Substrate Reagent Kit (Product # WP20005). An uncharacterized band was also observed at ~15kDa.