TC-A—induced apoptosis in B-CLL cells proceeds via caspases. EHEB cells were left untreated or pretreated with zVAD-fmk (1 hour) before application of the indicated concentrations of TC-A. After 24 hours, apoptosis was detected using the annexin V—FITC binding assay. The mean values representing the differences between TC-A—induced apoptosis minus spontaneous apoptosis of 4 independent experiments are shown.