Endodermal expression of GFP-Gpc4 restored JNK activation in gpc4 mutants. (A and B) The expression of Wnt5b and β-catenin (A), as well as p-JNK and JNK (B), as detected by Western blotting in the indicated embryos at 3 somite (s) stage from three or four independent experiments. (A′) Relative expression levels of Wnt5b versus β-catenin. (B′) Relative expression levels of p-JNK versus JNK. (C) Model of how endodermal GFP-Gpc4–labeled filopodia transport Wnt ligands to activate JNK in the mesoderm. Data are mean ± SEM. #, P > 0.05; *, P < 0.05; unpaired Student's t test.