FIGURE 4.

Bcl-2 and Bcl-xL are required for the protective effect of acidosis on glutamine starvation. Cells were electroporated with either nontargeting or both Bcl-2- and Bcl-xL-specific SMARTpool siRNA. A, extent of knockdown was assessed by Western blotting and B, cell viability was determined by trypan blue exclusion after overnight recovery from electroporation. C and D, after recovery as in A and B, cells were incubated for 8–10 h in the absence of 2 mm l-glutamine, with or without acidification of the medium. Cells were then tested for cell death or apoptosis by trypan blue exclusion (C) or Annexin V (D) positivity, respectively.