Smg6^{Gt(pU18)45Imeg}

The randomly integrating (within a gene) gene trap vector pU18 contains 1.8 kb of intron 1 and part of exon 2, including the splice acceptor, from the mouse engrailed 2 gene (En2) followed by an internal ribosome entry site (IRES) and the Betageo beta-galactosidase/neomycin resistance fusion gene with a mammalian polyadenylation signal. Three stop codons occur in the exon sequence upstream of and in frame with the Betageo translation initiation codon. Mutant and wild-type loxP sites used for 5' RACE analysis and for in vitro exchange of other sequences for Betageo are present. (J:109358, J:110088)