Furthermore, CLL is characterized by the expression of several markers specific to certain immune cells, such as ζ-associated protein kinase 70 (ZAP-70) (43) and lymphocyte-specific tyrosine kinase (Lck) (44), which favor CLL cell survival, and CD5, which maintains CLL cell anergy (45). Here, ZAP70 is linked to B-cell chronic lymphocytic leukemia.