FIG. 3.

Akt prevents the release of cytochrome c induced by multiple apoptotic stimuli. (A) Akt inhibits etoposide-mediated cytochrome c release. Rat1a (columns 1 and 2) and Rat1a/MyrAkt cells (columns 3 and 4) were either mock treated (columns 1 and 3) or treated with 10 μM etoposide (columns 2 and 4) for 3 h in the presence of 100 μM zVAD. Cells were then fixed and immunostained for cytochrome (cyto) c as described in Fig. 2. Averages (± standard errors) of at least 100 cells from four independent experiments are shown. (B) Akt inhibits Myc-mediated cytochrome c release. The percentage of cells demonstrating diffuse cytochrome c immunostaining was quantitated. Rat1a/MycER (columns 1 and 2) and Rat1a/MycER/MyrAkt cells (columns 3 and 4) were incubated overnight in DMEM with 2.5% FCS with (columns 2 and 4) or without (columns 1 and 3) 1 μM 4-HT. The next day, cells were placed in DMEM with 0.5% FCS and 100 μM zVAD for 3 h. Cells were then fixed and immunostained for cytochrome c as described for Fig. 2. Averages (± standard errors) of at least 100 cells from four independent experiments are shown.