JUNB expression and NF-κB activation in normal B cells. Immunofluorescence was performed for the c-Rel NF-κB subunit (red) and JUNB (green) on tonsillar sections. The upper panel shows a tonsillar GC (10 ×). The lower panels show the indicated GC regions at higher magnification (40 ×). In the DZ, B cells display cytoplasmic localization of NF-κB and absence of JUNB. In the LZ, a subset of CCs shows nuclear staining for c-Rel, and some of those cells coexpress JUNB (arrows).