Nuclear localization of NF-κB in bone marrow CD138⁺ multiple myeloma cells from patients. (A) Enriched CD138⁺ cells from bone marrow aspirates of different multiple myeloma patients were immunostained for NF-κB (p65) as described in “Patients, materials, and methods.” Red stain indicates the specific staining for NF-κB, whereas blue stain indicates a relative position of the nuclei in the corresponding view. Original magnification, × 200 (B) Enriched CD138⁺ cells (2 × 10⁶ cells) from bone marrow aspirates of multiple myeloma patients were tested for NF-κB activity in the nuclei by electrophoretic mobility shift assay as described in “Patients, materials, and methods.” Untreated or TNF-treated KBM-5 cells (TNF, 1 nM, 30 minutes) were used as negative and positive controls, respectively.