Bcl2 overexpression blocks apoptosis, Bid upregulation, and caspase-3 activation associated with Cdc42 and Rac1 deletion in NPM-ALK lymphoma. Three independent CreER^T2 lymphoma cell lines for each indicated genotype as in Figure 2 were transduced with a retrovirus expressing Bcl2 and GFP as reporter. Percentages of transduced cells were calculated by GFP positivity in flow cytometry and were above 90% in all cell lines. Cdc42 and Rac1 deletions were induced by treatment with 10 nM 4-hydroxytamoxifen for 4 hours. (A) Cells were collected at the indicated time points and lysed, and western blots were performed with the indicated antibodies. (B) Overexpression of Bcl2 rescues apoptosis induced by Cdc42 or Rac1 deletion. Three independent CreER^T2 lymphoma cell lines for each indicated genotype as in panel A were transduced with a retrovirus expressing Bcl2 and GFP. Cdc42 or Rac1 deletion was induced by 4-OHT treatment as described above. Analysis of apoptosis was carried out by TMRM staining and flow cytometry at the indicated time points. Data are indicated as mean ± SD of triplicate experiments, each performed with 3 independent cell lines for each genotype. P values are calculated by comparing control (Ctrl) vs 4-OHT–induced cells at each indicated time point (***P < .001).