Description
STAT proteins (Signal transducer and activator of transcription) belong to a family of cytoplasmic transcription factors that can be phosphorylated by a lignad binding to its cell surface receptor. Activation of STAT4 induces dimerization, nuclear translocation and DNA binding. STAT4 protein expression is restricted to the thymus, spleen and testis. Both tyrosine and serine residues on STAT4 become phosphorylated in response to IL-12 or IFN-alpha although serine phosphorylation is not required for DNA binding. STAT4 is activated in T-cells in response to the cytokine interleukin-12 (IL-12), and in NK cells by IL-2. STAT4-deficient mice display impaired IL-12 development of Th1 cells and enhanced development of Th2 cells