Signal transducer and activator of transcription 4 (STAT4) is a transcription factor belonging to the STAT protein family, composed of STAT1, STAT2, STAT3, STAT4, STAT5A, STAT5B, STAT6.[5] STAT proteins are key activators of gene transcription which bind to DNA in response to cytokine gradient.[6] STAT proteins are a common part of Janus kinase (JAK)- signalling pathways, activated by cytokines.STAT4 is required for the development of Th1 cells from naive CD4+ T cells[7] and IFN-γ production in response to IL-12.[8] There are two known STAT4 transcripts, STAT4α and STAT4β, differing in the levels of interferon-gamma (IFN-γ )production downstream.[9]
^Darnell JE, Kerr IM, Stark GR (June 1994). "Jak-STAT pathways and transcriptional activation in response to IFNs and other extracellular signaling proteins". Science. 264 (5164): 1415–21. Bibcode:1994Sci...264.1415D. doi:10.1126/science.8197455. PMID8197455.