Studies that were conducted over the last 15–20 years have provided compelling evidence that the BCR pathway is activated in CLL, DLBCL, Burkitt lymphoma (BL), follicular lymphoma (FL), mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), and Waldenstrom’s macroglobulinemia (WM) (Figure 2). This evidence concerns the gene BCR and Waldenstrom macroglobulinemia.