STAT2 is a transcription factor that mediates type I interferon (IFN-α/β) signaling, a critical component of antiviral immunity. Upon type I IFN receptor activation, JAK kinases phosphorylate STAT2, which then dimerizes with STAT1 and associates with IRF9 to form the ISGF3 transcription factor complex 1. This complex translocates to the nucleus and binds interferon-stimulated response elements (ISREs) to activate expression of over 300 interferon-stimulated genes (ISGs), driving cells into an antiviral state 2. Beyond canonical IFN signaling, STAT2 regulates mitochondrial fission and exhibits context-dependent roles in inflammation—functioning protectively in antiviral defense while potentially exacerbating chr12 inflammatory diseases when dysregulated 3. Clinically, complete STAT2 deficiency causes autosomal recessive immunodeficiency characterized by severe viral infections including critical influenza pneumonia, COVID-19 pneumonia, and HSV-1 encephalitis, with highest mortality in early childhood 2. Conversely, STAT2 activation promotes chemoresistance in ovarian cancer via the FBN1/VEGFR2/STAT2 axis, enhancing glycolysis and angiogenesis 4. Multiple viruses including Zika and Mpox exploit STAT2 degradation to evade innate immunity 56, while IL-20 suppresses pathogenic IFN/STAT2 signaling in inflammatory bowel disease 7. These findings demonstrate STAT2's dual role: essential for antiviral defense yet potentially harmful in chr12 inflammation and cancer.