Transcription factor that binds 5'-CNAATTAG-3' DNA sequence and regulates the expression of numerous genes including genes important for brain development (PubMed:7619729). During telencephalic development, causes ventralization of pallial progenitors and, depending on the developmental stage, specifies different neuronal fates. At early stages, necessary and sufficient to correctly specify the ventral lateral ganglionic eminence (LGE) and its major derivatives, the striatal projection neurons. At later stages, may specify LGE progenitors toward dorsal LGE fates, including olfactory bulb interneurons (PubMed:19709628). At 10.0 dpc, expressed in a band of primitive neuroepithelial cells in the neural tube, mesencephalon and telencephalon. At 11.5-13.5 dpc, expression is symmetrical, but tightly limited in areas of the forebrain, midbrain and hindbrain (PubMed:7619729). At 11 dpc, in the developing telencephalon, expressed at high levels in cells throughout the presumptive lateral ganglionic eminence (LGE), with an apparent ventral-to-dorsal gradient in expressing cell numbers. Positive cells are also scattered somewhat uniformly throughout the adjacent medial ganglionic eminence. At 12.5 dpc onward, exhibits a clear graded pattern of expression, with low levels found in cells located ventrally and the highest levels confined to those in the most dorsal portion of the LGE (at protein level) (PubMed:19709628). Expression decreases from 14.5 dpc on and becomes undetectable at 16.5 dpc (PubMed:7619729). Belongs to the Antp homeobox family.