Winged helix transcription factor BF-1 is essential for the development of the cerebral hemispheres

A mouse lacking Foxg1 expression was generated by replacing the coding sequencing with a lacZ/neomycin cassette; heterozygotes (only one copy of Foxg1 absent) were fertile and indistinguishable from wild-type littermates. Homozygotes were live born, but flaccid, with minimal spontaneous movements, and died shortly after birth.