WNT-induced ectopic Fgf8 expression was attenuated in Sp8 conditional knockouts.
(A–D) Whole mount Fgf8 expression on E12.5 GTs from embryos with genotypes indicated. Note the gradual reduction in Fgf8 expression in correlation with Sp8 allele number from B to D. (E) Real time-RT PCR analyses on E12.5 GTs with genotypes indicated. (F–H) Whole mount Fgf8 in situ on E11.5 limbs showing expanded expression in the AER-β-Cat-GOF mutant (G), and near normal expression in the GOF embryos with both Sp8 alleles abolished (H). (I–N) The autopod phenotype of AER-β-Cat-GOF mutants with (J, M) or without Sp8 (K, N) alleles. Quantification of digit numbers is shown in O.