Expression of c-REL messenger RNA and protein. (A) c-REL transcript levels in tumor cells from P3-L1, P4-L2, and P5L1 in comparison with ABC DLBCL and GCB DLBCL controls. The horizontal bar represents the mean value. (B-E) Immunohistochemical staining of c-REL on tumor biopsies (B,D: original magnification, ×400; C,E: detail from B and D, respectively). (B-C) A P4-L4 sample showing nuclear expression of c-REL in tumor cells and the absence of staining in endothelial cells. (D-E) A P4-L1 sample showing c-REL expression in both the nucleus and cytoplasm of tumor cells.