FIG. 4.

Interferon (IFN)-γ and interleukin (IL)-1β induce ip-10 synergistically. (A) Wild-type MEFs were treated with murine IL-1β (10 mg/mL) or IFN-γ (1,000 IU/mL) and RNA was analyzed by the Northern method. (B) Electrophoretic mobility shift assay (EMSA) was used to measure binding to the IFN-stimulated regulatory elements (ISRE) of ip-10 in response to treatment with IL-1β, IFN-γ, or both. (C) EMSA was used to measure binding to the two κB elements of ip-10 in response to IL-1β, IFN-γ, or both. By supershift analysis, the lower band was found to be a heterodimer of p65 and p50 and the upper band a p65 homodimer (data not shown).