Histone H3 lysine methylation is present across the interferon regulatory factor 1 gene ( IRF1 ) locus but is not dynamic in signal transducer and activator of transcription 1 (STAT1)-null cells. (a-e) Chromatin immunoprecipitation (ChIP) of U3A cells treated with interferon (IFN)γ for 30 min, or uninduced, and then collected at various time points. The indicated antibodies were used and quantitative PCR (Q-PCR) quantified the precipitate yield, reported as percentage of input. IgG served as the negative control. Locations of Q-PCR primers designed to span the entire locus of IRF1 are shown as in Figure 2h.