Immunoblotting with anti-SRSF2 antibody was performed as previously described (34 (link)). Briefly, cells were harvested and lysed with lysis buffer for 30 min at 4°C. The supernatants were collected and separated on 12% SDS-PAGE, and then transferred to PDVF membrane. After blocking with 5% skim milk, membrane was incubated anti-SRSF2 (Millipore) or anti-U2AF65 antibodies. The signal was detected by enhanced chemiluminescence (ECL).