Fig. 1.

Generation of a Gbx2-CreER-ires-Egfp knock-in allele. (A) Schematic representation of gene targeting strategy. The thick line in the targeting vector represents Gbx2 genomic DNA with an insertion of CreER-ires-Egfp-neo cassette at the 5′ untranslated region of the mouse Gbx2 gene. The selectable marker, neo, is flanked by two Frt sites (red triangles). (B) Southern blot identification of targeted ES cell clones using the 5′ and 3′ probes after digestion of genomic DNA with EcoRV restriction enzyme (RV). (C,D) Dorsal view of E18.5 Gbx2^CreER/+ (C) and Gbx2^CreER/- (D) brains. Arrow indicates the absence of the cerebellum in Gbx2^CreER/- embryos. cb, cerebellum; mb, midbrain. Scale bar: 1.7 mm.