The genomic fragment flanked by a single loxP site in intron 1 and a floxed neo cassette that had replaced exon 5 was excised from Rtn4tm3Matl via cre mediated recombination in the germline. The IRES-GFPLacZ cassette remained in exon 1. RT-PCR confirmed gene inactivation for all three isoforms. (J:83192, J:151085)