The targeting construct inserted a loxP site upstream of exon 2 and an FRT site, loxP site, 2A sequence, and a truncated (nonfunctional) NGFR reporter gene for cre-mediated deletion downstream of exon 5. FLP-mediated recombination removed the selection cassette inserted downstream of exon 5. NGFR expression is minimal even upon cre-mediated recombination thus cannot be used as intended. (J:313420)