The stained cells were resuspended in 890 µl PBS and added 10 µl 1 µM MTG (MitoTracker Green FM, Invitrogen A/S, Denmark) and 100 µl 1 µM TMRM (Tetramethylrhodamine methyl ester, Invitrogen A/S, Denmark). All stock solutions were dissolved in DMSO (dimethyl sulfoxide) and working solutions were diluted in PBS. After mixing samples were incubated for 30 minutes at room temperature in the dark.