Western blot was performed using Anti-Involucrin Polyclonal Antibody (Product # PA5-32454) and ~68kDa, ~75kDa, ~100kDa, ~124kDa bands corresponding to Involucrin was observed across skin derived cell lines tested (HaCaT and A-431) and not in others. Whole Cell Extract (30 µg lysate) of HaCaT (Lane 1), A-431 (Lane 2), HeLa (Lane 3), MDA-MB-231 (Lane 4), Raji (Lane 6) were electrophoresed using NuPAGE™ 10% Bis-Tris Protein Gel (Product # NP0301BOX). 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) using the iBright FL 1000 (Product # A32752). Chemiluminescent detection was performed using Novex® ECL Chemiluminescent Substrate Reagent Kit (Product # WP20005). IVL is reported to show this pattern of expression at molecular weights >68kDa and all of these forms are not detected in the low and/or negative cell lines tested [doi:10.1242/jcs.056093; 10.1093/toxsci/kfm153]