While IFNγ treatment, which relies on STAT1 signaling, does not activate IRF1 expression in these cells, infection with Pru(II) parasites does, and this activation is again dependent on the presence of GRA15 (Fig. 1D), demonstrating that the GRA15-mediated induction of IRF1 is through a different transcription factor. The gene discussed is STAT1; the disease is infection.