CXCR4 and classic Hodgkin lymphoma: Several studies have been performed to investigate the expression of chemokine receptors and their ligands in the HRS cells of cHL [15,16,17,18,19,20] These studies found that the chemokine receptors CCR5, CXCR3, CXCR4, CXCR5 and CCR7 are expressed in the HRS cells of cHL in a significant number of cases [15,18,19].