Conditional deletion of p53 cooperates with constitutive canonical NF-κB and Blimp1 loss in ABC-DLBCL lymphomagenesis. (A) Schematic diagram of the mutant mice and targeted B-cell functions used in this study. YC controls, YFP^stopF/+Cγ1^Cre/+; BIC, Blimp1^F/FIKK2ca^stopF/stopFCγ1^Cre/+; pBIC, p53^F/FBIC. (B) Overall survival of control or multilesion mice. (C) Representative immunohistochemical staining of hematoxylin and eosin, B220 and ki67 to label proliferating B cells in normal splenic GCs and murine diffuse B-cell lymphomas. Scale bars, 200 or 20 μm, as indicated. (D) RNA-seq gene expression classifier distinguishes ABC-DLBCL subtype in the murine lymphomas, which is confirmed by qRT-PCR of FACS-sorted reporter-positive normal GCBs or PCs, and lymphoma B cells (n≥3 animals). Relative values are normalized to GCB expression levels. (E) Scatter plot of differentially expressed genes (N = 1387) as measured by RNA-seq from GFP⁺/YFP⁺ reporter splenic B cells, showing log₂ fold-changes in lymphoma relative to normal GCBs (n ≥ 3 animals). Genes were stratified and colored according to whether they were found in both lymphoma models or differentially expressed in the more aggressive pBIC model. (F) Heat maps of gene expression levels (left) and gene ontology (GO) analysis (right) for the categories of differentially expressed genes stratified in panel E. (G) Comparative percentages of apoptotic cells within reporter-positive control or lymphoma cells. (H) Comparative percentages of reporter-positive B cells that are positive for γH2AX by intracellular FACS. Gray bars represent YFP/GFP-negative normal cells from the same tumors. (I) Bubble plot illustrating the enrichment of VDJ-IgH clonal groups within reporter-positive murine control or lymphoma cells that accumulate unique somatic mutations (y-axis) in intraclonally diverse V sequences (x-axis). Bubble sizes represent the abundance of clonal barcoded single-molecule, and therefore clon size, whereas colors indicate the dominant isotype.