AMD bindsexclusively to CXCR4,32 a receptor thatexhibits heterogeneous expression on MM cells.19 Despite this variability, studies have shown that 60% ofpatients with MM exhibit CXCR4-positive MM cells,20 highlighting the potential of ATBL for targeted drug delivery.To determine whether ATBL binds to MM cells and exerts a therapeuticeffect in vitro, we first analyzed the levels ofCXCR4, and its ligand SDF-1, in several MM cell lines. The gene discussed is CXCL12; the disease is Miyoshi myopathy.