Figure 3. Flt-1/VEGFR-1 conditional knockout targeting strategy.
A. The conditional VEGFR-1 targeting vector contained a 9.6 kb 5’ homology arm, floxed exon 3, an Frt (F, orange boxes) flanked neomycin resistance cassette (green box with a polyadenylation sequence (red box) at its 3’ end), a 4.7 kb 3’ homology arm, thymidine kinase cassette (TK, yellow rectangle), and the vector backbone (not shown). B. floxN allele which is the product of homologous recombination as shown in A. C. flox allele, generated by in vitro removal of the neomycin cassette by transfecting targeted ES cell clones with a Flpe expression vector.