Eμ-myc lymphomas overexpressing Bcl-2 and Bcl-X_L are sensitive to ABT-737–induced apoptosis. (A) 4242 Eμ-myc/MSCV and Eμ-myc/Bcl-2 lymphomas were treated with increasing concentrations of ABT-737 (top panel) or ABT-737e (bottom panel). Outer cell membrane disruption was assessed by uptake of PI. (B) 4242 Eμ-myc/Bcl-2, Eμ-myc/Bcl-XL, Eμ-myc/Bcl-w, Eμ-myc/Mcl-1, and Eμ-myc/A1 lymphomas were treated for 24 hours with increasing concentrations of ABT-737 or ABT-737e. Cell membrane disruption (left panels) and MOMP (right panels) were assessed by PI and TMRE staining, respectively. Results shown are the mean and SE from at least 3 separate experiments.