This gene encodes a member of the SOX (SRY-related HMG-box) family of transcription factors involved in the regulation of embryonic development and in the determination of the cell fate. The encoded protein may act as a transcriptional regulator after forming a protein complex with other proteins. Acts as transcription regulator that binds target promoter DNA and bends the DNA. Binds to the sequences 5'-AACAAT-'3 or 5'-AACAAAG-3'. Modulates transcriptional regulation via WNT3A. Inhibits Wnt signaling. Promotes degradation of activated CTNNB1. Plays a key role in the regulation of embryonic development. Required for normal development of the definitive gut endoderm. Required for normal looping of the embryonic heart tube. Plays an important role in embryonic and postnatal vascular development, including development of arteries. Plays an important role in postnatal angiogenesis, where it is functionally redundant with SOX18. Required for the generation and maintenance of fetal hematopoietic stem cells, and for fetal hematopoiesis. Probable transcriptional activator in the premeiotic germ cells.