FIG 2.

Luciferase reporter assay to evaluate transcriptional activation by GOF-STAT1 mutants. STAT1 mutants led to enhanced luciferase GAS-induced activity. Transcriptional responses to increasing concentrations of IFN-γ (white bar, nonstimulated; light gray bar, 10 U/mL; dark gray bar, 100 U/mL; black bar, 1000 U/mL) were added to U3C cells transfected with STAT1 mutants or WT STAT1 and cultured for 16 hours before GAS-induced activity was measured. Experiments were performed in triplicate, and data are expressed in relative luciferase units (RLU). Individual reporter assays were performed 3 times to confirm reproducibility. Y⁷⁰¹ mutation eliminated transcriptional activity of STAT1.