The STAT6 protein is a member of the STAT family of transcription factors that are activated by cytokines and phosphorylated by the receptor associated kinases. STATs form homo- or hetero-dimers that translocate to the cell nucleus where they act as transcription activators. STAT6 plays a central role in exerting IL4 mediated biological responses. STAT6 induces the expression of BCL2L1/BCL-XL, which is responsible for the anti-apoptotic activity of IL4. STAT6 mRNA has been detected in various tissues including peripheral blood lymphocytes, colon, intestine, ovary, prostate, thymus, spleen, kidney, liver, lung and placenta. STAT6 is critically involved in Th2 immune response.