BCR and B-cell chronic lymphocytic leukemia: Several lines of research have demonstrated beyond doubt that CLL can be subdivided into subgroups with distinct biological features, extending from genomic aberrations3 to immune signaling4 via receptor molecules of both innate (e.g. Toll-like receptors) and adaptive nature (i.e. the B cell receptor, BCR), with the latter so far thought to play perhaps a more pivotal role.2