IL-10 selectively inhibits transcription of the IP-10 gene. TG-elicted macrophages (1 × 10⁷ cells/sample) were stimulated with LPS (10 ng/mL) or IFNβ (500 U/mL) in the presence or absence of IL-10 (25 ng/mL) for 2 hours. In a separate experiment, macrophages were treated with LPS or IFNγ plus or minus IL-10. Nuclei were prepared and used in nuclear run-on assay as described in the legend to Fig 3. Similar results were obtained in two separate experiments.