Activation of STAT transcription factors in oncogenic tyrosine kinase signaling.

Signal transducers and activators of transcription (STATs) are cytoplasmic transcription factors that translocate to the nucleus and regulate gene expression in response to cytokine and growth factor stimulation. Emerging evidence indicates that STAT signaling is also frequently activated by oncogenes and in tumor cells. Constitutive activation of STAT proteins has been reported in cell lines stably transformed by diverse oncoproteins that directly or indirectly activate specific tyrosine kinase signaling pathways. In addition, STAT activation has been detected in a variety of human tumors and tumor cell lines, many of which are known to harbor activated tyrosine kinases. Recent findings support a model in which activation of STAT signaling in the context of oncogenesis induces gene expression that participates in malignant transformation.