Flow cytometry
The apoptosis ratio was estimated using the Dead Cell Apoptosis Kit with
Annexin V Alexa Fluor 488 for flow cytometry, following the
manufacturer’s instructions (Invitrogen, Carlsbad, USA). Cells were
collected, washed twice with cold PBS, and incubated with Annexin V-FITC
mixed with propidium iodide for 10 min in the dark. Cellular
fluorescence was assessed using flow cytometry (CytoFLEX S, Beckman,
China).