This transgene expresses Cre recombinase under the control of a human glial fibrillary acidic protein (GFAP) promoter. Cre-mediated recombination occurs primarily in the central nervous system, affecting astrocytes, oligodendroglia, ependyma and some neurons. Expression activity is also present in periportal cells of the liver. Developmental onset of transgene expression occurs in the dorsal and medial regions of the telencephalon by embryonic day 13.5. In adult cerebellum, only astrocytes are immunoreactive for GFAP or Cre recombinase.