Proteins were blotted onto a nitrocellulose membrane. The immunoblot was incubated with the primary antibody (anti-GFP antibody, Abcam) at 1:5,000 at room temperature for 1 hour and anti-IgG at 1:5000 for 1 h. After treatment with ECL (SuperSignal West Pico Plus Thermo Fisher Scientific) the GFP signal was detected with ImageQuant LAS4000 (GE Healthcare).