Peptide-induced Ca²⁺ oscillations in primary CLL cells. (A) Immunoblot comparing Bcl-2 levels in normal human B lymphocytes and 3 primary CLL samples. (B-D) Representative single-cell Ca²⁺ recordings illustrating the Ca²⁺ responses observed in CLL cells after addition (arrow) of 10μM of each peptide shown. Portions of the traces in panel D are magnified (insets) to illustrate the baseline Ca²⁺ elevation induced by TAT-IDP_DD/AA. (E) Percentage of CLL cells displaying Ca²⁺ oscillations in response to 10μM peptide addition during 90 minutes of single-cell recordings (mean ± SE, 3 experiments each using CLL cells isolated from a different patient, average 85 cells per experiment). (F) Amplitude of individual Ca²⁺ spikes in the same experiments shown in panel E (mean ± SE). (G) Inhibition of peptide-induced Ca²⁺ oscillations by xestospongin C summarized as percentage of CLL cells displaying Ca²⁺ oscillations during 90 minutes of single-cell recordings after the addition of TAT-IDP_DD/AA (5-10μM); cells were pretreated for 30 minutes with either DMSO (−) or 10μM xestospongin C (+) (mean ± SE, 4 experiments, average 75 cells analyzed per recording). (H) Failure of ABT-737 to induce Ca²⁺ elevation: (i) representative single-cell Ca²⁺ recordings in CLL cells, with arrow designating addition of 5μM TAT-Scr or TAT-IDP or 2μM ABT-737; (ii) percentage of CLL cells with Ca²⁺ oscillations in response to 5μM TAT-Scr or TAT-IDP or 2μM ABT-737, with symbols representing the mean ± SE in 2 experiments (average 80 cells per experiment); (iii) cell death (trypan blue dye uptake) in CLL cells incubated with or without 2μM ABT-737 for 24 hours, with symbols representing the mean ± SE in 7 experiments (average 400 cells counted per individual treatment).