Background
ETV4: ets variant gene 4 (E1A enhancer binding protein, E1AF), also known as PEA3. Several members of the Ets gene family are known to encode sequencespecific DNA binding proteins. These include mouse PU.1, mouse and human Ets-1, Drosophila E74, chicken and human Ets-2 and rat GABP-α. Each of these proteins recognizes similar motifs in DNA that share a centrally located 5'-GGAA-3' element. For instance, PEA3 binds the motif 5'-AGGAAG-3' (the PEA-3 motif), but does not bind to the sequence 5'-AGGAAC-3', recognized by PU.1, although PU.1 binds equally well to both sequences. It appears that all of the Ets proteins recognize the same central core sequence but that each protein interacts with unique sequences that flank this core. PEA3 is expressed at readily detectable levels in cells of epithelial and fibroblastic origin but is not expressed in hematopoietic cells. This is in contrast to other members of the Ets gene family, such as Ets-1, Ets-2 and Fli-1, each of which is expressed primarily in cells of hematopoietic origin.