The single coding exon was flanked by loxP sites. An EGFP reporter cassette, was inserted downstream of the floxed coding exon. Upon Cre-mediated recombination, the coding exon of the gene is replaced by the EGFP minigene that fails to express the endogenous encoded protein. A, frt-flanked neomycin resistance cassette was eliminated in vivo by crossing to a FLPe deleter strain. (J:251437)