The near total inhibition of migration toward CXCL12 observed in the presence of the CXCR4 antagonist (AMD) and the inhibitor of heterotrimeric G-proteins (PTX) illustrated the specificity of MM cell migration and confirmed that it was dependent on the interaction of CXCL12 with its receptor CXCR4 on the surface of MM cells. This evidence concerns the gene CXCL12 and Miyoshi myopathy.