Western blot was performed using anti-SMAD1 Polyclonal Antibody (Product # PA5-17122) and a 55 kDa band corresponding to SMAD1 was observed across the cell lines tested. Modified Whole cell extracts (30 µg lysate) (1% SDS) of T-47D (Lane 1), OVCAR-3 (Lane 2), HeLa (Lane 3) and HCT 116 (Lane 4) 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-Rabbit IgG (Heavy Chain) Superclonal™ 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).