ELF3 is a novel, highly tissue-restricted member of the ets transcription factor/oncogene family. ELF3 contains two putative DNA binding domains: an ETS domain, which is unique in that the 5' half shows relatively weak homology to known ets factors, and an A/T hook domain, found in HMG proteins and various other nuclear factors. In contrast to any known ets factors, ELF3 is expressed exclusively in epithelial cells. ELF3 is expected to be a critical regulator of epithelial cell differentiation. ETS factor ELF3 is a transcriptional regulator of angiopoietin-1 gene regulation in the setting of inflammation. ELF3 overexpressed early during human breast tumorigenesis. ELF3 expression confers a transformed and in vitro metastatic phenotype to otherwise normal MCF-12A cells. ELF3 mediates the expression of TGF-beta RII, and the transcriptional inhibition of ets-related transcription factor could be a one of the mechanisms of colonic carcinogenesis. ELF3 is positively and negatively modulated by other interacting proteins including Ku70, Ku86, p300, and CBP.