Fig. 1. Generation of Flk1^+/CreAlk3^{floxed/floxed} mice. (A) The mating scheme used to generate Alk3 CKO and control littermates. (B) (Upper) A 150 bp fragment from wild-type Alk3 allele and a 230 bp fragment from floxed Alk3 allele can be PCR-amplified with primers indicated by gray triangles (sense, 5'-GCAGCTGCTGCTGCAGCCTCC-3'; antisense, 5'-TGGCTACAATTTGTCTCATGC-3'). A 180 bp fragment should appear with primers indicated by black triangles (sense, 5'-GGTTTGGATCTTAACCTTAGG-3'; antisense, 5'-TGGCTACAATTTGTCTCATGC-3') if Cre-mediated recombination occurs. The presence of the knock-in Cre gene was confirmed by a 540 bp fragment using: sense, 5'-GAAACCGAGCTGCGTCCAGATTT-3'; antisense, 5'-GGTGTACGGTCAGTAAATTGG-3'. (Lower) A representative tail genomic DNA PCR results. Lane 1, Alk3^+/floxed; lane 2, Flk1^+/CreAlk3^+/floxed; lane 3, Flk1^+/CreAlk3^{floxed/floxed}. (C-J) Gross morphology of Alk3 CKO embryos. Scale bars: 1 mm.