Western blot was performed using Anti-Cathepsin D Polyclonal Antibody (Product # PA1-26253) and a 48 kDa band corresponding to Preprocathepsin D along with a 30 kDa band that corresponds to Cathepsin D heavy chain was observed across cell lines tested. Whole cell extracts (30 µg lysate) of MCF7 (Lane 1), Hep G2 (Lane 2), PANC-1 (Lane 3) and SK-BR-3 (Lane 4) were electrophoresed using NuPAGE™ 4-12% Bis-Tris Protein 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-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).