Effect of protein kinase inhibitors on apoptosis induced by CD20 cross-linking. 10⁶ Ramos cells/mL were incubated overnight with 0.125 to 0.5 μg/mL herbimycin A or 2.5 to 10 μg/mL genistein at 37°C. After washing twice with medium, cells were cultured with or without 10 μg/mL B1 anti-CD20 MoAb + 50 μg/mL GAM for 24 hours. Cell nuclei were stained with PI and analyzed by flow cytometry as described above. Cells treated with inhibitors only were used as controls. All wells contained comparable concentrations of dimethyl sulfoxide, which was used as a diluent to dissolve herbimycin A and genistein. The data are representative of three experiments.