The XIAP antagonist does not induce apoptosis in normal PBMC B-cells and does not sensitize DLBCL cells to etoposide. (A) DLBCL cell lines SUDHL4, SUDHL5, and HT were incubated with 25 μM XIAP antagonist (■), 500 nM etoposide (▩), or 10 μg/mL rituximab (□). Cell death was detected after 24 hours of incubation. (B) PBMC B cells of 3 healthy donors were treated with 25 μM XIAP antagonist (■), 500 nM etoposide (▩), or 10 μg/mL rituximab (□). Cell death was detected after 24 hours of incubation. (C) SUDHL4 cells were incubated with increasing concentrations of the XIAP antagonist either with or without 500 nM etoposide. Cell death was measured after 16 hours of incubation. Error bars represent SD of the mean value of 3 experiments.