Hras^tm1Jaf

The targeted locus consisted of 2 tandemly-arrayed murine Hras1 genes with the upstream wild-type copy flanked by loxP sites and the downstream copy containing a glycine-to-valine mutation at amino acid 12 (G12V). Between the two genes was placed a SV40 poly A sequence and a FRT-flanked neomycin selection cassette that was subsequently removed by crossing with transgenic mice expressing the FLPe recombinase. In the absence of cre expression, only the wild-type gene is expressed. In the presence of cre recombinase, the wild-type gene is excised and the mutant gene is instead expressed. (J:148393)