Immunofluorescent staining was conducted as described previously.52 (link) Briefly, at the indicated time points, cells were fixed with 4% paraformaldehyde for 15 min and permeabilized with 0.2% Triton X-100 (Beyotime, Shanghai, China) for 15 min followed by blocking with 10% goat serum (Beyotime, Shanghai, China) at room temperature for 1 h. Then, cells were incubated with the primary antibodies overnight at 4°C and then incubated with Cy3-labeled secondary antibody (BOSTER, Wuhan, China) or Alexa Fluor 488-labeled secondary antibody (Beyotime, Shanghai, China) for 1 h at 37°C in the dark. Subsequently, cells were stained with 4,6-diamidino-2-phenylindole (DAPI, Beyotime, Shanghai, China) for 10 min. Five random fields at 400 × magnification were photographed under a fluorescent microscope (Olympus BX53, Tokyo, Japan).