FCRL4 and cancer: RANKL expression has been reported in a FcRL4 positive subset of memory B cells present in the human tonsil.10 Fc-receptor-like-4 (FcRL4) is a transmembrane protein with homology to Fc receptors which is capable of aborting B cell receptor-mediating signalling and proliferation, and may therefore play an important role in the regulation of B cell activation and differentiation.11, 12 Expression of FcRL4 is restricted to B cells and across 950 cancer cell lines is only detected in B cell tumour lines (EBI Gene Expression Atlas).