The function of ENSG00000269404 (SPIB, Spi-B transcription factor) is as follows. Sequence specific transcriptional activator which binds to the PU-box, a purine-rich DNA sequence (5'-GAGGAA-3') that can act as a lymphoid-specific enhancer. Promotes development of plasmacytoid dendritic cells (pDCs), also known as type 2 DC precursors (pre-DC2) or natural interferon (IFN)-producing cells. These cells have the capacity to produce large amounts of interferon and block viral replication. May be required for B-cell receptor (BCR) signaling, which is necessary for normal B-cell development and antigenic stimulation. {ECO:0000269|PubMed:10196196, ECO:0000269|PubMed:12393575, ECO:0000269|PubMed:1406622, ECO:0000269|PubMed:15583020}.