Ext1^tm1.1Vcs

An inverted loxP site was introduced upstream to exon 2 in a genomic framgment containing the Ext1 gene. The fragment was then subcloned into a vector upstream of the forward-facing loxP-flanked neomycin resistance (Neo) cassette. The linearized targeting vector was electroporated into R1 ES cells. Homozygous Ext1tm1Kjns mice were crossed to Prxx1-cre transgenic mice that express cre in the germline. In some of the offspring, excision of the neo cassette only is the genetic consequence, leaving exon 2 flanked by inverted loxP sites. Homozygous animals are viable and fertile. (J:157599)