A targeting vector was designed to replace the stop codon of the endogenous LIM homeobox protein 8 (Lhx8) gene with (from 5' to 3') a viral 2A oligopeptide (to mediate ribosomal skipping), cre recombinase, another 2A oligopeptide, the cerulean variant ofgreen fluorescent protein (GFP), and a bovine polyadenylation sequence.