Rituximab-induced CDC in JY/WT and BTZ-resistant JY cells. Cells were incubated with increasing concentrations anti-CD20/rituximab (range; 0.1 μg-50 μg/ml) and 5% baby rabbit complement serum. Cell viability (% lysis) was measured after 1 hour using propidium iodide (PI) staining and FACS analysis. Results depicted are means ± SD of 5–8 separate experiments. *** p < 0.001, ** p < 0.01.