LoxP sites were inserted to flank the Foxg1 coding sequence. In addition, a Flpe gene was inserted 3' of the downstream loxP site, into the 3'end of the endogenous gene. An adjacent frt-flanked neomycin selection cassette was removed via Flp-mediated recombination. Upon cre-mediated recombination, Flpe is expressed from this locus. (J:188355)