Following Ficoll-Hypaque gradient centrifugation, plasma cells obtained from the bone marrow were isolated from the mononuclear cell fraction by immunomagnetic bead selection using a monoclonal mouse anti-human CD138 antibody (Miltenyi-Biotec, Auburn, CA). More than 90 percent of the cells used for gene expression profiling were plasma cells, as shown by two-color flow cytometry using CD138+/CD45- and CD38+/CD45- markers, the presence of cytoplasmic immunoglobulin light chains by immunocytochemistry, and morphology by Wright-Giemsa staining. MRI-lytic-lesion sample Keywords = multiple myeloma, osteolytic lesions, MRI, osteoblast, mesenchymal stem cell, Wnt signaling, DKK1