Based on the extent of CXCR4 downregulation in response to sustained BCR stimulation, our cohort of 73 CLL patients was divided into 2 groups with one characterized by a high response (> 5%; n = 58) and another one with low response (≤ 5%, n = 15) (Supplementary Table S1). The gene discussed is CXCR4; the disease is B-cell chronic lymphocytic leukemia.