Cellular proteins were extracted using RIPA buffer supplemented with 1 mM PMSF. Proteins concentrations were determined kit (Beyotime institute of Biotechnology). Equal amounts of sample lysate were separated using 8% SDS-poly gel electrophoresis(SDS-PAGE) and transferred onto polyvinylidene fluoride(PVDF) membranes. After incubation with primary antibodies including rabbit polyclonal anti-Drosha (Abcam) and mouse monoclonal anti-beta-actin, blots were incubated with goat anti-rabbit or anti-mouse secondary antibody. Finally, signals were detected using a chemiluminescence ECL detection system (pierce)