Fig 8.
SPPV14 inhibits both Bax and Bak and functionally compensates for endogenous prosurvival Bcl-2. (A) SPPV14 inhibits both Bak- and Bax-mediated apoptosis. Shown is the viability of SPPV14-expressing Bak- or Bax-deficient MEFs treated for 24 h or 48 h with etoposide (10 mM). (B) Selectivity of BH3-only proteins for mammalian prosurvival Bcl-2 proteins (9, 58). (C) SPPV14 potently inhibits apoptosis even if all endogenous mammalian prosurvival Bcl-2 proteins are neutralized. Shown is colony formation of parental or SPPV14-expressing wild-type or Bax- or Bak-deficient MEFs infected with the Mcl-1-selective ligand BimS2A (43) and cotreated with ABT-737 (1 μM), a combination that inactivates all endogenous mammalian prosurvival proteins expressed in MEFs (9, 67). The data in panels A and C represent means and SD from 2 independent experiments using a clone of each genotype.