Transcription repressor. Required for the specification of corticospinal motor neurons and other subcerebral projection neurons. May play a role in layer and neuronal subtype-specific patterning of subcortical projections and axonal fasciculation. Controls the development of dendritic arborization and spines of large layer V pyramidal neurons. Plays a role in rostro-caudal patterning of the diencephalon and in prethalamic formation. Highly expressed in neocortical layer V, moderately expressed in layer VI. Expressed in subcortically projecting neurons. Expressed in the olfactory epithelium, hypothalamus, ventrolateral pallium and prethalamus at mid-gestation. At 12.5 dpc, highly enriched in the postmigratory pyramidal neurons forming the cortical plate situated beneath the pial surface. At 13.5 dpc, expressed in the ventricular zone and subventricular zone at low levels, expression is much higher in the developing cortical plate, where postmitotic neurons are positioned. During late embryonic and early postnatal development, expression disappears from cortical progenitors and becomes restricted to the subplate and the prospective layer V and VI pyramidal neurons. In null mutant mice, no subcerebral projection neurons are born and no cortical projections to the brainstem or the spinal cord ever develop. In contrast, other populations of neurons are unaffected. There seems to be a redundant role for FEZF1 and FEZF2 in diencephalon development. Belongs to the krueppel C2H2-type zinc-finger protein family.