F3^tm1Fct

The open reading frame was replaced with one encoding the soluble alternatively spliced form and a loxP flanked neomycin resistance cassette. After homologous recombination into ES cells, the floxed neomycin resistance cassette was removed by transfection with a Cre expression plasmid. mRNA expression of the soluble form was 5.9-fold higher in homozygous mutant embryos relative to wild-type embryos, whereas mRNA expression of the full-length form was undetectable in homozygous mutant embryos. Western blot analysis revealed comparable protein expression of the soluble form in E9.5 homozygous mutant and wild-type embryos. (J:216519)