IRF4 targets the IECS.

<p>(A) Reporter assays of transcription through the IECS. Tot2 cells were transduced with SIRV-IECS-Ld40-GFP or SIRV-mIECS-Ld40-GFP and then with empty MSCV-CD8t, MSCV-IRF4-CD8t, or MSCV-IRF8-CD8t. The promoter activities in CD8⁺ cells were analyzed on day 2 after the transduction of MSCVs. The activity is shown as mean fluorescent intensity (MFI) of GFP signals (mean ± standard deviation of three independent experiments). *<i>P</i><0.01 (Student's <i>t</i>-test). (B, C) ChIP assays for binding to the IECS (B) or a gene promoter containing an IECS (C). Cells transduced with SIRVs and MSCVs were analyzed by ChIP assays on day 3 after the transduction of MSCVs. Chromatin was precipitated by anti-IRF4 antibody, anti-IRF8 antibody, or normal goat IgG. Precipitated DNA was analyzed by qPCR in triplicate using primers that amplified the IECS sequence in SIRVs or those that amplified the IECS region of the <i>Cst3</i> gene promoter (mean ± standard deviation). Data are representative of three independent experiments. *<i>P</i><0.01 (Student's <i>t</i>-test).