Transcription factor that binds to DNA at the consensus sequence 5'-ACCAAAG-3' (By similarity). Acts as a transcriptional activator (By similarity). Binds cooperatively with POU3F2/BRN2 or POU3F1/OCT6 to gene promoters, which enhances transcriptional activation (By similarity). Involved in the differentiation of naive CD4-positive T-cells into peripherally induced regulatory T (pT reg) cells under inflammatory conditions (By similarity). Binds to the promoter region of the FOXP3 gene and promotes its transcription, and might thereby contribute to pT reg cell differentiation in the spleen and lymph nodes during inflammation (By similarity). Plays a redundant role with SOX4 and SOX11 in cell survival of developing tissues such as the neural tube, branchial arches and somites, thereby contributing to organogenesis (By similarity). Expressed most abundantly in the CNS (PubMed:9215677). Expressed in the heart, pancreas, thymus, testis and ovary (PubMed:9215677). Weakly expressed in brain, placenta, lung, liver, skeletal muscle, kidney, spleen, prostate, small intestine, colon, and peripheral blood lymphocytes (PubMed:9215677). Expressed in the fetal brain, lung, liver, and kidney.