Transcription factor expressed by neural progenitor cells in specific regions of the embryonic neuroepithelium. Essential for the mammillary nuclei maintenance. Negatively regulates the proliferation of oligodendrocyte progenitors and promotes oligodendrocyte maturation. Also expressed in mammary glands, plays a role in lactation, controls development of mammary glands and the inferior colliculi of the midbrain in the central nervous system that regulates the milk-ejection reflex. . This is the function of Ensembl gene identifier ENSG00000171956 (FOXB1, forkhead box B1).