Sensitivity to the XIAP antagonist in relation to expression of Bcl-2. (A) Bcl-2 expression was detected in all the DLBCL samples tested using RT-MLPA analysis. Patient samples were divided into 2 groups: samples with an LD₅₀ less than 39 μM or LD₅₀ of 39 μM or greater. Horizontal lines represent the mean Bcl-2 expression level for each group. (B) Expression of Bcl-2 after transfection with siControl or siBcl-2 RNA in SUDHL4 cells. Shown are the results after 72 hours of transfection. (C) Percentage cell death after 4 hours of incubation with 10 μM XIAP antagonist in SUDHL4-transfected cells with siControl or siBcl-2 RNA. Error bars represent SD of the mean value of 3 experiments.