FIG. 6.

Multiple BH3 peptides cooperate with c-Myc to induce cell death in Bax-deficient cells. (A to C) bax^−/− MEFs infected with pBp(c-MycER^TAM) were treated with either ethanol vehicle control or 100 nM OHT to activate c-Myc 2 h prior to microinjection with 2 mg of Bax-BH3 (A), Bak-BH3 (B), or Bid-BH3 (C) peptide per ml. Cell death was assessed as described in the legend to Fig. 4A. Data are the mean values ± SEM from at least three independent experiments. Each experiment comprised two paired observations as described in the legend to Fig. 5A. (D) Additional experiments were performed as described for panels A to C by using bax^−/−/bak^−/− MEFs infected with pBp(c-MycER^TAM). (E) bax^−/− MEFs infected with pBp(c-MycER^TAM) were microinjected with pcDNA3(Bak) (100 ng/ml) and pEGFP-N1 (20 ng/ml). The number of GFP-expressing cells was evaluated by fluorescence microscopy 18 h after microinjection. Cells were then washed twice in PBS and treated with 100 nM OHT or ethanol vehicle control in the absence of FCS. Cell loss was evaluated at the times indicated, as described in the legend to Fig. 1A. The data presented are mean values ± SEM from three independent experiments.