Strong nuclear ATF3 expression is a hallmark of non-GC and ABC DLBCL patients. (A) Relative mRNA expression of ATF2, ATF3, and ATF7 in ABC vs GCB DLBCL biopsies. Error bars indicate standard error of the means (SEMs). (B) Immunofluorescence staining of ATF3 expression and localization in the indicated GCB and ABC DLBCL cell lines. Bar, 5 μm. (C) Histologic staining of ATF3 expression in representative biopsy samples of DLBCL patients. Bar, 50 μM; magnification, ×400. (D-E) TMA analysis of DLBCL biopsies previously categorized into GCB or non-GC using the Hans algorithm (D), or into ABC or GCB by GEP (E). Bar graphs summarizing the classification of non-GC and GCB patients (D) or ABC and GCB patients (E) according to staining intensity (weak, intermediate [int.], and strong) and subcellular localization of ATF3 (C, cytoplasmic; N, partially or predominantly nuclear). Analysis was performed on 28 (D) or 17 (E) patients with nodal (lymph node) tumors. DAPI, 4,6 diamidino-2-phenylindole.