STATs, Signal Transducers and Activators of Transcription, are transcription factors that are phosphorylated by JAK kinases (JAKs) in response to cytokine activation.

Then they dimerize and move into the nucleus to activate transcription of cytokine-responsive genes.

There are at least 3 JAKs and at least six STATs, with different cytokines inducing different patterns of JAK and STAT activation.

See also

References

 Clevenger CV. Roles and regulation of stat family transcription factors in human breast cancer. Am J Pathol. 2004 Nov;165(5):1449-60. PMID: #15509516#

 Aaronson DS, Horvath CM. A road map for those who don't know JAK-STAT. Science. 2002 May 31;296(5573):1653-5. PMID: #12040185#