OCT1, OCT2, and OBF1 colocalize with TFs of the ETS family. (A) De novo motif analysis for Bio-ChIP-seq peak regions of OCT2 (top), OBF1 (middle), and OCT1 (bottom) in LPS-stimulated CD19⁺ mouse splenic B cells. Sequence logos and P values are shown for the most highly enriched sequence motifs. (B) Enrichment of Octamer motifs in OCT1, OBF1, and OCT2 in 500-bp windows centered on peak summits. Controls are randomly shuffled peak sequences that retain dinucleotide frequency. (C) Enrichment of PU.1 binding motifs (MA0080.3 in JASPAR database) in 500-bp windows centered on OCT1, OBF1, and OCT2 peak summits. Controls are randomly shuffled peak sequences that retain dinucleotide frequency. (D) Occurrence of PU.1 binding motif in a 500-bp window surrounding Octamer motifs in OBF1 overlapping peak regions. The black line shows the occurrences of original motifs within 500 bp around octamer motifs found in OBF1 peaks. Gray lines show the occurrences of randomly shuffled ETS motifs as backgrounds. Each of the original ETS motifs were randomized 500 times. After randomization, P value was calculated by comparing the 95th percentile of the occurrences of original motifs with the 95th percentiles of all randomly shuffled ETS motifs (500 times for each motif). (E) Venn diagrams showing overlaps between OCT1/OCT2/OBF1 peaks and PU.1 ChIP-seq peaks. (F) Average expression (log₂ counts per million, x-axis) and change of expression (log₂-fold change, y-axis) for genes in WT and OBF1 knockout CD19⁺ splenic B cells stimulated with LPS. Differentially expressed genes are color-coded (DEGs fold change ≥1, FDR <0.01, logCPM >2): red data points represent genes with higher expression level in OBF1 knockout cells; green data points represent genes with higher expression in wild type cells. (G) Average expression (log₂ counts per million, x-axis) and change of expression (log₂-fold change, y-axis) for genes in WT and PU.1 knockout CD19⁺ splenic B cells stimulated with LPS. Differentially expressed genes are color-coded (DEGs fold change ≥1, FDR <0.01, logCPM >2): red data points represent genes with higher expression level in PU.1 knockout cells; green data points represent genes with higher expression in WT cells. (H) Venn diagrams showing the overlaps between significantly upregulated (top) and downregulated (bottom) genes identified in OBF1 and PU.1 knockout B cells under LPS treatment. All samples in this figure were LPS-stimulated CD19⁺ mouse splenic B cells.