Naturally occurring NDMs cooperate with oncogenic Myc to promote B-cell lymphomagenesis in vivo. (A) Mutant enrichment in B-cell–purified preneoplastic Eµ-myc transgenic splenocyte preparations in vitro (n ≥ 3 spleens from 4-week-old transgenic mice with no signs of lymphadenopathy), retrovirally transduced with the indicated NDM (coexpressing GFP) or an empty vector, respectively. The initial percentage of GFP⁺, GhostRed⁻ (ie, viable) B lymphocytes was adjusted to 8.0% ± 4%. After 3 days in culture, the relative changes in the fraction of GFP⁺ and viable cells were measured. Error bars denote the standard deviation. (B) Eµ-myc transgenic murine FLCs, a source of HSCs, were stably transduced with mutant moieties as in panel A, and IV transplanted into lethally irradiated strain-matched mice. Recipient mice were monitored for up to 300 days until lymph nodes became well palpable. Shown here is the fraction of GFP⁺ Eµ-myc lymphomas detected in each mutant cohort, with the number of mice under observation indicated for every cohort. (C) Tumor latencies reflecting the time between HSC transplantation and first-time detectability of a palpable lymphadenopathy for empty vector (ie, GFP⁻; n = 19) or the indicated mutants (all GFP⁺; n = 18 [MyD88] and n = 13 [NFKBIZ]); P < .0001 for each mutant compared with empty vector. (D) NDMs interfere with Myc-induced apoptosis in HSC-generated Eµ-myc–driven lymphomas in vivo. Percentages of apoptotic B-lymphoma cells (TUNEL⁺/B220⁺) in n ≥ 3 individual cases per genotype (with error bars denoting the standard deviation). TUNEL, terminal deoxynucleotidyl transferase dUTP nick-end labeling.(E) Principal component (PC) analysis of transcriptome profiles in n ≥ 3 individual HSC-derived Eµ-myc lymphoma cases per genotype. Asterisks indicate significance (P < .05).