Expression and regulation of MALT1 protease–dependent genes in ABC DLBCL. (A) Differential gene expression for n = 414 cases (167 ABC-like DLBCL, 64 unclassified, and 183 GCB-like DLBCL; Gene Expression Omnibus accession GSE10846) for the genes ZC3H12A, NFKBIZ, and NFKBID in ABC, unclassified, and GCB DLBCLs. (B) Relative transcript expression of ZC3H12A, NFKBID, and NFKBIZ by qRT-PCR in a panel of ABC and GCB DLBCLs; n ≥ 3, all error bars depict the mean ± SD. (C) Western blot analysis of MALT1 substrates Regnase-1 and Roquin-1/2 and their targets IκΒζ and IκBNS in a panel of ABC and GCB DLBCL cells. Unspecific bands are marked with an asterisk. (D-E) Western blot analysis of (D) ibrutinib- or (E) MLT-748–treated ABC DLBCL. Activity of the MALT1 protease was determined by cleavage of Regnase-1 and Roquin-1/2 and their targets IκBζ and IκBNS. “L” and “S” depict long and short IκBζ isoforms, respectively. Unspecific bands are marked with an asterisk. (F) Transcript analysis of ZC3H12A, NFKBIZ, and NFKBID after inhibition with ibrutinib or MLT-748 in ABC DLBCL. n = 4, all error bars depict the mean ± SD; ordinary 1-way ANOVA with Dunnett multiple comparisons; ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; and ∗∗∗∗P < .0001.