The function of ELF3 (E74 like ETS transcription factor 3, Ensembl gene identifier ENSG00000163435) is as follows. 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). {ECO:0000250, ECO:0000269|PubMed:10391676, ECO:0000269|PubMed:10644990, ECO:0000269|PubMed:10773884, ECO:0000269|PubMed:11036073, ECO:0000269|PubMed:11313868, ECO:0000269|PubMed:12414801, ECO:0000269|PubMed:12624109, ECO:0000269|PubMed:12682075, ECO:0000269|PubMed:12713734, ECO:0000269|PubMed:14715662, ECO:0000269|PubMed:14767472, ECO:0000269|PubMed:15075319, ECO:0000269|PubMed:15169914, ECO:0000269|PubMed:15794755, ECO:0000269|PubMed:16307850, ECO:0000269|PubMed:17060315, ECO:0000269|PubMed:9129154, ECO:0000269|PubMed:9234700, ECO:0000269|PubMed:9336459, ECO:0000269|PubMed:9395241, ECO:0000269|PubMed:9417054}.