The E26 transformation-specific (ETS) family of transcription factors comprises of 27 and 26 members in humans and mice, respectively, which are known to regulate many different biological processes, including cell proliferation, cell differentiation, embryonic development, neoplasia, hematopoiesis, angiogenesis, and inflammation. The epitheliumspecific ETS transcription factor-1 (ESE-1) is a physiologically important ETS transcription factor, which has been shown to play a role in the pathogenesis of various diseases, and was originally characterized as having an epithelial-restricted expression pattern, thus placing it within the epithelium-specific ETS subfamily. Despite a large body of published work on ETS biology, much remains to be learned about the precise functions of ESE-1 and other epithelium-specific ETS factors in regulating diverse disease processes. Clues as to the specific function of ESE-1 in the setting of various diseases can be obtained from studies aimed at examining the expression of putative target genes regulated by ESE-1. Thus, this review will focus primarily on the various roles of ESE-1 in different pathophysiological processes, including regulation of epithelial cell differentiation during both intestinal development and lung regeneration; regulation of dendritic cell-driven T-cell differentiation during allergic airway inflammation; regulation of mammary gland development and breast cancer; and regulation of the effects of inflammatory stimuli within the setting of synovial joint and vascular inflammation. Understanding the exact mechanisms by which ESE-1 regulates these processes can have important implications for the treatment of a wide range of diseases. KEYWORDS: cancer; development; epithelial cell differentiation; ESE-1; ETS transcription factor; inflammation; regeneration The E26 transformation-specific (ETS) family of transcription factors is characterized by a highly conserved 84-aminoacid DNA-binding domain, known as the ETS domain. 1 Because the first member of the ETS family, the v-ets oncogene, was originally discovered as part of a fusion protein with gag and myb expressed by the E26 avian erythroblastosis-transforming retrovirus and its DNA-binding domain is E26 transformation-specific, this 84-amino-acid DNA-binding domain was named the ETS domain. 1 The ETS domain is usually located within the carboxyl-terminal region of the protein as a winged helix-turn-helix structural motif and mediates binding to sites of purine-rich DNA, commonly containing a core consensus sequence of GGAA/T, within the promoter and enhancer regions of target genes. 2,3 Many ETS transcription factors also contain a pointed domain, which is located within the amino-terminal region and is involved in protein-protein interactions. 2 Approximately 30 members of the ETS transcription factor family have been identified in mammals (ie 27 in humans and 26 in mice), 4 and have been shown to play crucial roles in the regulation of many physiological and pathological processes, such as embryonic develo...