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). The gene discussed is BCR; the disease is marginal zone lymphoma.