Immunoblotting was conducted similarly to those published previously (32 (link), 33 (link)). Briefly, cells were washed once with pre-warmed 1X PBS and then lysed directly with ice-cold lysis buffer containing 50 mM Tris-HCl (pH 7.4), 150 mM NaCl, 1 mM EDTA, 1% (v/v) NP-40, 0.5% sodium-deoxycholate, and Complete™ protease inhibitor cocktail (Roche Diagnostics, Indianapolis, IN). Whole cell lysates (50 μg) were resolved on a 10% SDS-PAGE (BioRad, Hercules, CA) and transferred to a nitrocellulose membrane (Santa Cruz Biotechnology, Inc., Dallas, TX). The membrane was probed with the following antibodies: mouse polyclonal anti-FLAG antibody (1:4000 dilution), mouse monoclonal anti-β-actin antibody (1:5000 dilution) (Sigma Aldrich, St. Louis, MO), and mouse monoclonal anti-GAPDH antibody (1:5000 dilution) (Santa Cruz Biotechnology, Inc., Dallas, TX). The nitrocellulose membrane was then probed with an anti-mouse HRP-conjugated secondary antibody (Cell Signaling, Danvers, MA). The signal was detected using Supersignal West Dura (Pierce, Rockford, IL) with a BioRad ChemiDoc XRS imaging system (BioRad, Hercules, CA). All primary and secondary antibodies were diluted in 1X TBST. Expression of protein and loading control densitometry analysis was performed using Image Lab v4.1 software (BioRad, Hercules, CA).