Immunoblotting was performed as described (Lin and Tarn, 2011 (link)). We used affinity-purified polyclonal antibodies against RBM4 (Lin and Tarn, 2011 (link)), α-tubulin (GenScript, Piscataway, NJ), glyceraldehyde 3-phosphate dehydrogenase (GAPDH; Proteintech, Rosemont, IL), and FLAG (Sigma-Aldrich).