IRF1 and infection: To address this, we utilized real-time quantitative PCR to examine the expression of known STAT1-dependent genes triggered by IFNγ stimulation, including the transcription factor interferon regulatory factor 1 (Irf1)[28], [29], and members of the p47 GTPase family known to be essential for survival during in vivo infection, Lrg-47 and Igtp[17], [20], [57], [58].