Moreover, we recently described how mimicking the microenvironment ex vivo leads to the upregulation of ZAP-70 protein in primary CLL cells and how the small percentage of Ki-67 positive cells in peripheral blood (PB) of patients with ZAP-70 are highly enriched in CLL cells expressing ZAP-707. The gene discussed is MKI67; the disease is B-cell chronic lymphocytic leukemia.