This strain was made by electroporation of DAc8 embryonic stem cells with a targeting vector containing 6.0kb 5' and 1.8kb 3' homology arms and a FRT-CAG-Pac-FRT cassette. The FRT-CAG-Pac-FRT cassette is inserted into the intron between Il2rg 4th and 5th exon. No genomic sequence is deleted. Chimeras were formed by microinjecting into F344 blastocysts. Founder animals were mated with SD rats to produce this strain.