Comparison of sensitivity to doxorubicin between MDM2-transfected EU-4 cells and control cells.

(A) Parental EU-4 cells and cells stably transfected with either CMV-MDM2 plasmid (EU-4 MDM2 from clone shown in Figure 2, lane 6) or CMV-neo plasmid (EU-4/neo) were cultured with different concentrations of doxorubicin for 48 hours, and cell survival was determined by XTT assay. (B) Results of Western blot assay for activation of caspase-3 and cleavage of its substrate, PARP, in EU-4 MDM2 and EU-4 neo cells that were treated with doxorubicin at 1.5 μM for indicated times. Anti–caspase-3 antibody recognized the 32-kd unprocessed proprotease and the 20-kd subunit. Anti-PARP detected an 85-kd fragment cleaved from the 116-kd PARP holoenzyme.