Figure 2.
BCL-XL overexpression sequesters BIM and BAK and impairs S63845 mediated apoptosis induction. (A) Immunoblot analysis of the indicated BCL-2 family members was performed 24 hours (h) post-treatment initiation. One representative experiment of three independent biological replicates is shown. (B) BAK activation in MM.1S was determined by staining with antibodies against its active form. (C) MM.1S cells transduced with pcW57.1 EGFP (left panel) or pcW57.1 BCL-XL (right panel) were treated for 24 h with 0.5 μg/mL doxycycline to induce protein overexpression and afterwards exposed to the indicated treatments. Apoptotic cells were assessed 24 h post- treatment induction. Results indicate the mean +/- standard deviation of the mean (SDM) of three independent experiments. Differences between groups were calculated with one-way ANOVA, corrected for multiple comparison with Bonferroni-Holm correction with ****P<0.0001, **P<0.001 and *P<0.05. (D and G) Co-immunoprecipitation experiments in MM.1S cells transduced with either pcW57.1-EGFP (right panels) or pcW57.1-BCL-XL (left panels) were performed after 24 h pretreatment with 0.5 μg/mL doxycycline to induce protein overexpression and subsequent drug exposure for 24 h.