Fig. 2.

Expression of NF-κB subunits in mouse brain tumors. Brain tumor tissue slices were obtained from severe combined immundeficient mice in which U-87MG cells were injected into the brain and were co-stained with p65 antibody (a,e), p50 antibody (b,f), and DAPI (c,g). Merged images shown in d and h. p65 antibody showed exclusive staining in tumor cells, clearly demarcating tumor mass from the normal brain tissue (a). Diffuse p50 expression was observed in tumor cells as well as in neighboring normal brain cells (b). Higher magnification revealed clear difference in intracellular distribution of p65 and p50. While primarily p65 staining was strong in the cytoplasm and largely absent in nuclei of the tumor cells (arrows, e), p50 staining was weak in the cytoplasm but concentrated in areas overlapped with DAPI staining indicating localization in nuclei of tumor cells (arrows, g). In contrast, p50 is absent in nuclei of the endothelial cells (arrow head) surrounding capillary blood vessels (*). a–d: 10× magnification; e–h: 20× magnification.