UPR activation in CLL/SLL LNs. Immunohistochemical analysis of expression of (A,C,F) PERK, (B,D,G) XBP1, and (E,H) Ki-67 in (A-B) multiple myeloma and (C-H) CLL/SLL LNs. Original magnification of images are shown. Results are representative of a total of 11 biopsies analyzed. CLL PCs are circled, and higher-magnification images of the PC marked (*) in C and D are shown in F and G. The inset in G shows the nuclear expression of XBP1 in the small CLL cells in contrast to the cytoplasmic expression in the large blasts in the PCs. Arrows highlight large blasts in F and G. Images for C and F (PERK) and D and G (XBP1) are from samples 8 and 11, respectively. Inset shown in G is from sample 1.