FIG. 8.
bcl-X suppression is necessary for Myc to trigger apoptosis following γ-IR. Wild-type and p53−/− MEFs were transduced with MSCV-Myc-ER-IRES-GFP- and MSCV-hBcl-XL-IRES-YFP-expressing viruses, and doubly transduced MEFs were compared to those expressing Myc-ER alone. (A) GFP-only- or Myc-ER-expressing MEFs were treated with 4-HT (1 μM) for 24 h and irradiated with 5 Gy, and viability was determined by trypan blue dye exclusion at the indicated intervals. Viability experiments shown are representative of three independent experiments performed in triplicate. (B) Immunoblot analysis with an antibody specific for human Bcl-XL (left panels) demonstrated that overexpression of human Bcl-XL protein was sustained in Myc-expressing cells exposed to γ-IR, contrary to results with endogenous mouse Bcl-XL (right panels).