The FCCP titration (2–12.5 μM) of ZAP-70+ CLL cells demonstrated that they were more sensitive to FCCP compared to ZAP-70− CLL cells or B lymphocytes, achieving a maximal respiratory capacity at 5.32 ± 1.91 μM, as opposed to 8.50 ± 2.42 μM in B lymphocytes and 7.18 ± 2.43 μM FCCP in ZAP70− CLL cells (Figure 4H), demonstrating their increased sensitivity to perturbations of the ETC. This evidence concerns the gene ZAP70 and B-cell chronic lymphocytic leukemia.