Figure 4.

Effect of the signal tranducer and activator of transcription 1-S727A mutation on the expression of the endogenous Mx1 and Gbp1 genes during transient transfection. Stat1-deficient fibroblasts were co-transfected with Stat1-α or Stat1-S727A and a plasmid that drives expression of the β-galactosidase gene (β-Gal). Some of the transfected cells were used for measuring β-Gal activity in cell extracts to ensure comparable transfection efficiencies. The remaining cells were either left untreated or were treated with interferon-β (IFN-β) for 4 h, after which total RNA was isolated and processed for real-time quantitative PCR analysis of the expression of the Mx1 and Gbp1 genes. Inducibility is calculated as the ratio of expression measured in IFN-β-treated and untreated cells.