Firstly, we observed that the Ki-67 positive fraction of CLL cells from the PB was significantly enriched in ZAP-70 positive cells (Figure 4A) (mean % of ZAP-70 expression: 83.93±2.40 in Ki-67 positive cells vs. 29.22±4.20 in Ki-67 negative cells, P<0.001). Here, ZAP70 is linked to B-cell chronic lymphocytic leukemia.