sFRP-2 is expressed by MM cells of patients with bone destruction. (A) Expression of sFRP-2 mRNA by MM cells isolated from patients with advanced bone disease was detected by RT-PCR. Total RNA (2 μg) extracted from primary cells was reverse transcribed, and 1 μL of the 20-μL reaction was used in PCR analysis for sFRP-2 and GAPDH mRNA. (B) The isolated MM cells were cytospun and stained with anti–sFRP-2 antibody or nonimmune IgG as described in “Patients, materials, and methods.” Cells were visualized under an Olympus BX50 microscope equipped with a UMplanFI 40 ×/0.75 objective lens (Olympus, Tokyo, Japan) to achieve an original magnification of 400 ×. Images were recorded with an Olympus SC35 CCD camera and Viewfinder Lite software (Pixera, Los Gatos, CA), and were digitally processed with Adobe Photoshop software (Adobe Systems, San Jose, CA).