The association of the FcμR with CLL has long been suggested based on: (i) the ability of CLL cells to form rosettes with IgM-coated erythrocytes [47,48], (ii) IgM binding to CLL cells, as monitored by flow cytometry [49,50], and (iii) the expression of elevated levels of FCMR transcripts by microarray and RT-PCR analyses [43,44]. The gene discussed is CD40LG; the disease is B-cell chronic lymphocytic leukemia.