ZAP70 was shown to increase B-cell receptor signaling and increase the responsiveness of ZAP70-positive B-CLL cells to CCL19 and CCL21 with enhanced migratory capacity toward CCR7 compared to ZAP70-negative cells, which was associated with F-actin polymerization, migration and lymph node involvement [271,272,273]. Here, CCL21 is linked to B-cell chronic lymphocytic leukemia.