p50 and p52 expression in patient MM cells. (A) Immunohistochemical analysis for p50, p65, and p52 expression was performed on BM tissue microarrays from healthy donors, persons with MGUS, and MM patients. Representative results are shown. CD138 is stained in red; p50 and p52 is stained in brown. Immunohistochemical studies were performed on consecutive serial tissue sections from archival paraffin-embedded bone marrow biopsies from normal individuals (NBM), as well as patients with MGUS and MM. Tissue sections were incubated with either anti-p50, -p65, or -p52 Abs, and immunoreactivity was visualized with peroxidase stains. Histologic micrographs were taken using a Leica DM200 microscope (aperture HC PLANs 10×/22, objective lenses: N PLAN 100×/1.25 oil), and a SPOT Insight QE model camera with SPOT Advanced acquisition software (Diagnostic Instruments, Sterling Heights, MI). (B) Nuclear extracts from patient MM cells were immunoblotted with anti-p52, -p65 Abs. p84 served as a positive control for nuclear protein.