Fig. 2.

Floxed Gα₁₃ allele. (A) Diagram of WT Gα₁₃ locus, targeting vector, recombined locus along with FLPe-excised “flox” allele, and Cre-excised “Δ4” null allele. Shaded rectangles indicate FRT sites; other conventions are as in Fig. 1. Shown at Bottom is the constitutive null Gα₁₃ allele (“-”) described in ref. 17. Sizes of the DNA fragments detected by Southern hybridization with either Exon 1 (blue) or Exon 4 (orange) probe after NcoI/EcoRV digestion are shown in Bottom.(B) Southern blot analysis of tail DNA from adult mice with the indicated Gα₁₃ genotypes: WT (+), exon 1 constitutive null (-), flox (f), exon 4 deletion null (Δ4). The probes used are indicated at the top. The DNA in lane 8 was obtained from a β-actin-Cre transgene-positive mouse; note the absence of the 2.3 kb Gα₁₃ flox allele band and the presence of the ≈10.0 kb Gα₁₃ Δ4 allele band. (C) Efficient endothelium-specific excision by Tie2-Cre. Tie2-Cre^Tg/o;ROSA26R embryos collected at E9.5 were X-Gal stained. Virtually all endothelial cells were lacZ positive. (Scale bar: 1 mm.)