On-chromatin MAF cooperation with IRF4 and MAF-dependent expression of IRF4. (A) Heatmap and histogram of MAF and IRF4 ChIP-seq in MM.1S myeloma cells, indicating peaks shared and specific to each transcription factor. ChIP-seq peak intensity in reads per kilobase per million mapped reads. (B) Reads per kilobase per million mapped reads browser plots of key MAF target genes showing the binding of MAF in MM.1S (red), JJN3 (light blue), and H929 (green) as well as IRF4 in MM.1S (dark blue). MAF ChIP-seq tracks represent FC over input, with horizontal bars below tracks indicating peaks with q < .01. IRF4 ChIP-seq tracks represent normalized ChIP-seq signal (bars showing peaks, with q < .01). (C) ChIP-qPCR against IRF4 of the same target genes in MM.1S cells, against IgG control, expressed as percent input DNA. Bars represent mean + standard error of the mean of n = 4 experiments. (D) Heatmap illustrating the MAF-associated regions found to be cobound by IRF4. IRF4 ChIP-seq data in MM.1S are illustrated in purple (IRF4 ChIP-seq). In red, MAF binding on the MAF-associated regions in MM.1S (MAF ChIP-seq). In blue, the ATAC-seq peaks obtained from the 2 primary MAF myeloma samples (MAF_s1 and MAF_s2), compared with the peaks found in healthy PCs (ND1, ND2, and ND3, in gray). (E) Pie charts depicting the percentage of MAF-associated, MAF-activated and the validated by overexpression experiments MAF-activated regions cobound by IRF4 (black). (F-G). Reciprocal ChIP-re-ChIP for MAF and IRF4 at promoters or putative enhancers, respectively, of the gene targets shown (n = 2).