DAPI Staining Assay for Nucleus Condensation

The DAPI staining assay was conducted to detect possible occurrence of nucleus condensation in the treated cells. Briefly, the treated cells were fixed with the freshly prepared ice-cold paraformaldehyde (4%) and then exposed to 0.1% Triton X-100 in PBS for 5 min for permeabilization. They were subsequently stained with DAPI (1 μg/mL in PBS) for 5 min in the dark. After removing the surplus stain, the cells were washed (3×) using 0.1% Triton X-100 in PBS. The image acquisition was performed by Olympus IX81 invert fluorescence microscope equipped with Olympus DP70 camera (Olympus Corp., Tokyo, Japan) as described previously [27 (link)].