BAX/BAK Independent Cell Death Figure 1. BH3 peptides induce cell death in Bax2/2/Bak2/2 MEFs. (A) Percentage of cell death measured by LDH release at 24 hours following treatment of wild type and Bax2/2/Bak2/2 MEFs with BID or mutant BID BH3 peptide (50 mM and 100 mM). Mean values6SEMs of 3 independent experiments are shown. (B) Percentage of LDH release from wild type and Bax2/2/Bak2/2 MEFs after treatment with BIM (40 mM and 80 mM) or PUMA (50 mM and 100 mM) BH3 peptide for 24 hours. Mean values6SEMs of 3 independent experiments are shown. (C) Wild type and Bax2/2/Bak2/2 MEFs were treated with NOXA BH3 peptide (75 mM), BAD BH3 peptide (30 mM), NOXA BH3 peptide (75 mM)+BAD BH3 peptide (30 mM) or NOXA BH3 peptide (75 mM)+mutant BAD BH3 peptide (30 mM). Cell death was measured by LDH released at 24 hours. Mean values6SEMs of 3 independent experiments are shown. (D and E) Percentage of PI positive Bax2/2/Bak2/2 MEFs and Bax2/2/Bak2/2 Baby Mouse Kidney (BMK) epithelial cells after 1 hour of treatment with BID BH3 peptide (100 mM), mutant BID BH3 peptide (100 mM) or BIM BH3 peptide (80 mM). Mean values6SEMs of 3 independent experiments are shown. doi:10.1371/journal.pone.0005646.g001 (Figure 5B). On the contrary, treatment of wild type MEFs with BID or BIM BH3 peptides but not the mutant BID BH3 peptide induced the release of cytochrome c into the cytosol as detected by the presence of cytochrome c in the supernatant fraction (Figure 5A). This data further indicate that Bax2/2/Bak2/2 MEFs cell death is not through the release of cytochrome c. PLoS ONE | www.plosone.org 3 May 2009 | Volume 4 | Issue 5 | e5646