Prosenescent phenotypes of MyD88 and CARD11 mutations in Myc-driven lymphomagenesis. (A) Percentages (left) of SA–β-gal⁺ cells in cytospin preparations of n ≥ 3 individual cases per indicated genotype (with error bars denoting the standard deviation) of B220⁺-purified B-lymphoma cell populations at the time of lymphoma manifestation. Representative photomicrographs of SA–β-gal stainings (right). Scale bars, 100 µm. (B) As in panel A, but lymphoma sections were stained for H3K9me3 and hematoxylin and eosin (H&E). Scale bars, 100 µm. (C) As in panel A, but lymphoma sections stained for Ki67 (H&E stain). Scale bars, 100 µm (identical magnification throughout the figure). (D) GSEA for terms “SASP” and “senescence“ (supplemental Table 2) in RNA-seq–based GEP of lymphoma cells as in panel A; P < .05 and false discovery rate (FDR) <0.25 indicates significance. (E) Fractions of SA–β-gal⁺ cells within B220⁺- and GFP-sorted lymphocytes isolated 3 months after transplantation (with no signs of manifest lymphoma) from spleens of Eµ-myc transgenic HSCs stably transduced with GFP-coexpressing CARD11-L225LI, CARD11-L244P, or an empty vector construct as control (left; n = 4 for each mutant; error bars denote the standard deviation). Representative photomicrographs of SA–β-gal stainings (right). Scale bars, 100 µm. (F) Tumor latencies in recipients of Eµ-myctransgenic and Suv39h1-deficient HSCs infected with either the CARD11-L244P mutant, MyD88-L265P mutant, or an empty vector for comparison (n ≥ 4 each; CARD11-L244P;suv39h1^−/− vs empty vector;suv39h1^−/−P = 0.0018, MyD88-L265P;suv39h1^+/+ vs MyD88-L265P;suv39h1^−/− [median survival 36 vs. 20 days; compare to Figure 1C] P < 0.001). Asterisks indicate significance (P < .05). NES, normalized enrichment score; n.s., not significant.