DNMT1 is highly expressed in GC B cells. (A) Relative transcript abundance of DNMT1, DNMT3A, and DNMT3B as well as the GC B-cell specific transcripts PCNA and BCL6 were measured by QPCR. The y-axis depicts the fold difference of relative expression of each transcript in GC B cells versus NB cells. (B) Immunoblotting with anti-DNMT1 antibody was performed in GC B cells and NB cells as indicated, using actin as loading control. (C-F) Immunohistochemical double-staining in reactive human tonsillar tissue delineates expression of DNMT1 (dark purple nuclear staining), (C) in the germinal center CD79A⁺ (membranous brown staining) B cells and not in (D) CD68⁺ (membranous brown staining) tingible-body macrophages or (E) IgD⁺ (membranous brown staining) NB cells, or (F) CD3⁺ (membranous brown staining) T cells.