Western blot was performed using Anti-Cullin 4A Polyclonal Antibody (Product # PA5-17101). An 87 kDa band along with a 77 kDa band, which is a reported isoform corresponding to CUL4A was observed across cell lines tested and increased upon TGF-beta 1 treatment in A549. Modified whole cell extracts (1% SDS) (30 µg lysate) of MDA-MB-231 (Lane 1), MCF-7 (Lane 2), A549 (Lane 3), A549 treated with TGF-beta 1 (10 ng/mL for 24 hr) (Lane 4), LNCaP (Lane 5), HeLa (Lane 6) and Hep G2 (Lane 7) 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™ 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).