Identification of a B-cell network of FOXP1 target genes. (A) Heatmaps and line charts representing the top-scoring FOXP1 target genes clustered with respect to their expression profiles in naïve (n = 2), GC (n = 2), and memory (n = 2) human B cells (columns). FOXP1 expression pattern (cluster 2) was included in the analysis for comparison purposes. (B) Validation of FOXP1 occupancy at representative target genes as measured by quantitative ChIP in the OCI-ly1 cell line and in tonsillar naïve B cells. Data are displayed as average fold enrichment relative to the input in 3 independent experiments. (C) FOXP1 canonical and secondary binding motifs detected by the FIRE motif discovery algorithm in our list of FOXP1-bound promoters. (D) Venn diagram showing overlapping between the FOXP1 and BCL6 target genes discovered by our ChIP-on-chip approaches. (E) Transcriptional changes in representative FOXP1 target genes after 48-hour siRNA-mediated knockdown of FOXP1 in OCI-ly1 cells, as evaluated by qRT-PCR in 3 independent experiments. Bars represent gene expression normalized to GAPDH and displayed as fold change relative to scramble-siRNA–treated samples. A representative western blot demonstrating a reduction of FOXP1 protein expression is shown on top.