E1AF is a member of the ETS oncogene family and is thought to be a human homologue of mouse PEA3. We have isolated a genomic clone of E1AF and analyzed the Promoter activity of its 5'-flanking region. We identified a variation in exon 1, which depends on the cell type. There was no typical TATA box in the 5'-flanking region, but putative binding sites of a number of transcription factors including PEA3 as well as CAAT boxes were seen. A luciferase reporter assay indicated that the 5'-flanking region possesses promoter activity. Northern blot studies demonstrated significant expression of the E1AF gene in restricted tissues such as the pituitary gland, placenta, and fetal kidney. Moreover, the E1AF promoter was activated by E1AF itself and estrogen receptor. These findings suggest that E1AF is a housekeeping gene, whose expression is controlled in specific tissues. (c) 2005 Elsevier Inc. All rights reserved.