Targeting of EGFP cDNA to the proviral ROSA26 locus and its expression after Cre-mediated excision of Stop and PGK-CD/PGK-Puro sequences.

(A) Structures of gene-trapped ROSA26 locus, targeting construct, and floxed ROSA26-EGFP locus. The positions of selection cassettes, the Stop fragment, and 3 loxP sites with the same orientation are indicated. E, EcoRI; P, PacI, X,XbaI, SA, splicing acceptor. Positions of probes used to identify and confirm structures are also indicated. (B) EGFP expression in E10.5 and E13.5 wild-type (WT) and excised ROSA26-EGFP embryos. (C) EGFP expression in organs in 1-week-old wild-type or excised ROSA26-EGFP mouse.