Inhibition of IFN-γ–induced STAT1 activation by JAB. Cells (A; M1-derived cells, B; NIH3T3-derived cells) were stimulated with or without IFN-γ (1,000 IU/mL) for the indicated periods and lysed. The postnuclear supernatant was subjected to immunoblotting with anti–tyrosine-phosphorylated STAT1 (PY-STAT1) or anti-STAT1 (STAT1) and to EMSA with IRF-1 probe (EMSA).