Ca²⁺ chelators inhibit apoptosis induced by hypercross-linking CD20. 10⁶ Ramos cells/mL were incubated with 3 mmol/L EGTA or 3 mmol/L EGTA plus 5 μmol/L Bapta AM for 30 minutes at 37°C before incubation with 10 μg/mL antibodies for 24 hours in the presence or absence of GAM cross-linker (50 μg/mL). Cell nuclei were stained with PI and analyzed by flow cytometry. Hypodiploid DNA peaks corresponding to apoptotic nuclei were quantified, and results presented as antibody-mediated apoptosis minus spontaneous apoptosis. Cells that were not pretreated with either EGTA or Bapta were used as controls. Data are representative of four experiments.