Examination of STAT-1 DNA-binding activity in mouse TBCs exposed to IFN-γ. A, WCE were prepared from NIH-3T3, SM9, and M-11 cells incubated with IFN-γ for 0, 1, 3, 6, and 24 h, and subjected to EMSA using radiolabeled oligonucleotides corresponding to GAS from the mouse IRF-1 promoter. The gels were exposed to phosphor screens and scanned with a Storm scanner to generate the figure shown, which is representative of three independent experiments. B, The phosphor screen was scanned, and the intensity of the bands was quantified by Image J software. C, Competition experiments were performed using 40× excess of unlabeled GAS double-stranded oligonucleotides (40× UC), or unlabeled mutated GAS oligonucleotides (40× mUC) that are incapable of being bound by STAT-1. They were incubated with SM9 cell extracts before radiolabeled GAS oligonucleotides. D, A total of 4 µg of STAT-1 supershift Abs (ss) was added immediately after WCE isolated from SM9 and M-11 cells were incubated with the radiolabeled GAS oligonucleotides.