Transcriptional activator that binds and transactivates ETS sequences containing the consensus nucleotide core sequence GGA[AT]. Acts synergistically with POU2F3 to transactivate the SPRR2A promoter and with RUNX1 to transactivate the ANGPT1 promoter. Also transactivates collagenase, CCL20, CLND7, FLG, KRT8, NOS2, PTGS2, SPRR2B, TGFBR2 and TGM3 promoters. Represses KRT4 promoter activity. Involved in mediating vascular inflammation. May play an important role in epithelial cell differentiation and tumorigenesis. May be a critical downstream effector of the ERBB2 signaling pathway. May be associated with mammary gland development and involution. Plays an important role in the regulation of transcription with TATA-less promoters in preimplantation embryos, which is essential in preimplantation development (By similarity). Interacts with TBP. Interacts with CREBBP and EP300; these act as transcriptional coactivators of ELF3 and positively modulate its function. Interacts with XRCC5/KU86 and XRCC6/KU70; these inhibit the ability of ELF3 to bind DNA and negatively modulate its transcriptional activity. Associated with CLND7 and POU2F3 (By similarity). Belongs to the ETS family.