Fos^{tm2(Fosl1)Wag}

Exon 1 of the Fos locus was replaced with the entire Fosl1 coding sequence followed by stop codons. A floxed neo cassette was inserted for selection and subsequently excised from ES cells via cre mediated recombination. Because Fos mRNA levels are in part controlled by a destabilizing region in the 3' UTR, Fos sequence downstream of the Fosl1 insertion was left intact, though affected by a frameshift mutation introduced by the insertion. The lack of aberrant transcripts was verified by RT-PCR analysis. RNAse protection assays confirmed that the expression pattern of the inserted Fosl1 recapitulated that of the endogenous Fos gene. (J:65766)