Figure 1.

Targeted disruption of the PAPP-A gene locus. A, Targeting strategy used to disrupt the PAPP-A locus. Homologous recombination (represented by X) between the targeting vector and the PAPP-A gene results in the substitution of a LoxP-flanked exon 2 along with a Frt-flanked selection cassette. B, Southern hybridization indicating proper gene targeting in the ES cell clones. Clone 2G11 was used for blastocyst injections; Lex-1 represents untransfected ES cell DNA. These are spliced images.