Although the mechanisms by which rituximab successfully depletes lymphoma and other CD20+ malignancies do not appear to affect CD20+ B cells or circulating CD20+ plasma cells in MM, use of other agents to target CD20 on the MM B cell compartments, for example radiolabeled anti-CD20 (Zevalin) or a radiolabeled anti-CD19, might prove useful in MM. This evidence concerns the gene CD19 and lymphoma.