The protein encoded by this gene is a member of the STAT protein family.In response to cytokines and growth factors,STAT family members are phosphorylated by the receptor associated kinases,and then form homo- or heterodimers that translocate to the cell nucleus where they act as transcription activators.This protein can be activated by various ligands including interferon-alpha,interferon-gamma,EGF,PDGF and IL6.This protein mediates the expression of a variety of genes,which is thought to be important for cell viability in response to different cell stimuli and pathogens.Two alternatively spliced transcript variants encoding distinct isoforms have been described.[provided by RefSeq,Jul 2008]