Augmented LUBAC expression accelerates oncogenic MYD88-mediated B-cell lymphomagenesis in mice. (A) Association of HOIP (RNF31) expression with cell of origin in human DLBCL. Boxes represent the median and the first and third quartiles, and whiskers represent the minimum and maximum of all data points. (B) Schematic representation of conditional expression of HOIP in mice. (C) Transcript levels of NF-κB target genes in unstimulated splenic B cells from mice (10 weeks old), normalized against Actb messenger RNA; n = 3 per genotype. Data are presented as means ± standard deviation (SD). (D) Cell Trace Violet–labeled splenic B cells were cultured with or without stimuli. (E) Cell lysates of splenic B cells derived from CD19-cre, CD19-cre-MYD88LP, and CD19-cre-HOIP/MYD88LP mice were subjected to Halo-tagged linear ubiquitin-specific tandem ubiquitin binding entity (M1-specific TUBE) binding and Halo tag–based purification and analyzed by immunoblotting. (F) Kaplan-Meier plots of survival of transgenic mice (n = 18, CD19-cre; n = 36, CD19-cre-HOIP; n = 26, CD19-cre-MYD88LP; and n = 33, CD19-cre-HOIP/MYD88LP). (G-I) Representative tumor involvement of lymphoid organs isolated from 9-month-old CD19-Cre-MYD88LP and CD19-cre-HOIP/MYD88LP mice. (G) Macroscopic appearance of spleens (left) and lymph nodes (right). (H) Representative H&E and immunohistochemical staining for Irf4 and Bcl6 of spleens (CD19-cre mice) or tumors (CD19 cre-MYD88LP and CD19-cre-HOIP/MYD88LP mice). Scale bars represent 200 μm (inset 20 μm). (I) Representative analyses of clonality. Tumor 1084–specific primers specifically amplified tumor 1084–specific V(D)J but did not amplify V(D)J from genomic DNA of normal splenic B cells or tumor 786. *P < .05, **P < .01, and ***P < .001, 2-tailed unpaired Student t test (A and C) or log-rank test (F). See also supplemental Figures 1 and 2 and supplemental Table 1. CpG, cytosine guanine dinucleotide; FPKM, fragments per kilobase million; HA, hemagglutinin; n.s., not significant; Spl, splenic; wt, wild-type.