A targeting vector containing (5' to 3'): human BRCA1 exons 2 to 14 - loxP site - F3 mutant FRT site - Puromycin cassette - F3 mutant FRT site - human BRCA1 exons 15 to 23 - mouse Brca1 3' UTR - HGHpA - loxP site - human mutant BRCA1 exons 15 to 23 (including the 5382insC point mutation in exon 19) - mouse Brca1 3' UTR - HGHpA - FRT - NEO cassette - FRT, was used to replace the coding region in exon 2 and the splice donor-site in intron 2 of the mouse Brca1 gene. Transient flp-mediated recombination removed both the puro and neo cassettes. (J:240315)