Cfp^tm1Song

A targeting vector was constructed where a loxP site was inserted upstream of exon 3, and a FRT flanked neomycin resistance cassette followed by a loxP site was inserted downstream of exon 5. Upon recombination, the neomycin cassette inserted in the intended location but the upstream loxP site failed to recombine. Analysis of chimeric mice revealed that the insertion of the neomycin cassette was sufficient to prevent transcription of the targeted gene. Gene inactivation was confirmed by failure to detect the gene product in the sera of homozygotes by an immunodiffusion assay. (J:130108)