Transcriptional activator that binds to the consensus sequence 5'-AACAAAG-3' in the promoter of target genes and plays an essential role in embryonic cardiovascular development and lymphangiogenesis. Activates transcription of PROX1 and other genes coding for lymphatic endothelial markers. Plays an essential role in triggering the differentiation of lymph vessels, but is not required for the maintenance of differentiated lymphatic endothelial cells. Plays an important role in postnatal angiogenesis, where it is functionally redundant with SOX17. Interaction with MEF2C enhances transcriptional activation. Besides, required for normal hair development. Interacts (via C-terminus) with MEF2C (via MADS box). Detected in heart, lung, placenta, skeletal muscle, liver, kidney, spleen, prostate, ovary, msosmall intestine and colon. Binds target DNA via the HMG box domain. The 9aaTAD motif is a transactivation domain present in a large number of yeast and animal transcription factors. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Was originally termed SOX-8.