Signal Transducer and Activator of Transcription 1-Alpha/Beta (STAT1) contains one SH2 domain and belongs to the transcription factor STAT family. When tyrosine- and serine-phosphorylated, STAT1 can form a homodimer termed IFN-gamma-activated factor (GAF), migrate into the nucleus and bind to the IFN gamma activated sequence (GAS) to drive the expression of the target genes, inducing a cellular antiviral state. STAT1 functions as signal transducer and transcription activator that mediates cellular responses to interferons. Defects in STAT1 are the cause of STAT1 deficiency complete and familial candidiasis type 7.