(A) BCMA mRNA expression levels relative to HPRT in purified splenic B cells and representative FACS plots of BCMA protein expression by B cells and PCs in the spleens of 4-mo-old mice are shown. NS, not significant. n = 5–6 mice. (B) Immunoblot analysis of cytoplasmic extracts prepared from 24 hr stimulated cells was performed using antibodies against p100, p52, and β-actin. Nuclear extracts were probed with antibodies recognizing p52, p65, and HDAC1. Data shown are representative of three individual experiments.