In vivo kinetics of five CXCR4/CD5 intraclonal fractions: To dissect CLL intraclonal kinetics in greater detail, CD19+CD5+ cells from 10 patients with CLL were sorted based on the relative densities of CXCR4 and CD5 to define five fractions. The gene discussed is CXCR4; the disease is B-cell chronic lymphocytic leukemia.