Western blot was performed using GRK2 Polyclonal Antibody (Product # PA5-77852) and a 80 kDa band corresponding to GRK2 was observed across cell lines and tissue extracts along with an uncharacterized band (*) at ~140 kDa in the cell lines tested. Whole cell extracts (30 µg lysate) of HEK293 (Lane 1), MCF7 (Lane 2), Jurkat (Lane 3), THP1 (Lane 4), tissue extracts (30 µg lysate) of Mouse Cerebellum (Lane 5), Mouse Spleen (Lane 6) and Mouse Heart (Lane 7) of Fig a; and MCF7 (Lane 1), MCF10A (Lane 2), Mouse Spleen (Lane 3) and Mouse Heart (Lane 4) of Fig b were electrophoresed using 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 (1:1,000 dilution) and detected by chemiluminescence with Goat anti-Rabbit IgG (Heavy Chain), Superclonal™ Recombinant Secondary Antibody, HRP (Product # A27036, 1:4,000 dilution) using the iBright FL 1000 (Product # A32752). Chemiluminescent detection was performed using Novex® ECL Chemiluminescent Substrate Reagent Kit (Product # WP20005).