Zinc finger nuclear factor involved in transcription by regulating chromatin structure and organization (PubMed:20219459, PubMed:21570965). Involved in the pluripotency and differentiation of embryonic stem cells by regulating SOX2, POU5F1/OCT4, and NANOG (PubMed:21570965). By binding PBX1, prevents the heterodimerization of PBX1 and HOXA9 and their binding to DNA (PubMed:17353115). Regulates neuronal development and neural cell differentiation (PubMed:21570965, PubMed:27621227). Interacts with PBX1 isoform PBX1b; this interaction prevents PBX1-HOXA9 heterodimer from forming and binding to DNA. Expressed in the cerebral cortex (at protein level) (PubMed:17207666, PubMed:27621227). Expressed in embryonic stem cells (at protein level) (PubMed:20219459). Expressed in heart, liver, kidney, muscle, and female and male genital tracts (at protein level) (PubMed:27621227, PubMed:17353115). Detected at 6.5 days post coitum (dpc) in the developing central nervous system (PubMed:17207666). At 7.75 dpc, expression is limited to the headfolds (PubMed:17207666). At 8 dpc, transcripts are detected in the midline neural groove (PubMed:17207666). Between 8 dpc and 9.5 dpc, it is found in the developing forebrain, brainstem, spinal cord, branchial arches, otic vesicles, midbrain and hindbrain folds (PubMed:17207666, PubMed:17353115). At 10.5 dpc, expression is detected in the telencephalic vesicles, branchial arches, otic vesicles, dorsal root ganglia, somites, spinal cord and forelimb buds, specifically in migratory muscle progenitor cells (PubMed:17207666). At 11.5 dpc, it is detected in telencephalic vesicles, midbrain-hindbrain boundary, the spinal cord, branchial arches, dorsal root ganglia, fore- and hindlimb buds and somites (PubMed:17207666, PubMed:17353115). Also detected at 11.5 dpc throughout the wall of the telencephalic vesicle and the medial and lateral ganglionic eminence (PubMed:17353115). At 14.5 dpc, expression is detected in the entire cerebral cortex, with higher levels in the developing hippocampus and septal area (PubMed:17207666). Expression becomes more graded by 16.5 and 18.5 dpc, where it is detected in the caudal and medial cerebral cortex, hippocampus and retrosplenial cortex (PubMed:17207666). Detected at 16.5 dpc in female genital tract (PubMed:17353115). It is also detected in the olfactory bud at 18.5 dpc (PubMed:17207666). Detected at 9.5 dpc in embryos (PubMed:20219459). Detected from 7.5 dpc in the brain, with highest levels of expression being detected at postnatal day 1 (PubMed:27621227). Expression remains at high levels at postnatal day 7 and begins to decrease by postnatal day 14 (PubMed:27621227). Expression is decreased further by postnatal day 30 (PubMed:27621227). Embryonic lethal (PubMed:27621227). Knockout mice do not develop past 18.5 days post coitum and exhibit smaller sized eyes with neural-tube defects (PubMed:27621227). Heterozygous mice exhibit decreased expression and delayed development (PubMed:27621227). Heterozygous mice grow slower, weigh less than wild-type mice and have significantly reduced brain weight (PubMed:27621227). They also exhibit lowered levels of PBX1 and HOXB8 (PubMed:27621227). Mice also exhibit anxiety-like behaviors with excessive grooming, resulting in gradual hair loss (PubMed:27621227).