xCdc4ΔFbox inhibits neural crest specification. xCdc4ΔFbox or xCdc4 mRNA (1 ng) was injected into one cell of two-cell-stage embryos. GFP mRNA (1 ng) was injected as a control, and β-gal mRNA was injected as a lineage tracer (light blue unilateral staining). (A-F) Embryos were allowed to develop to stage 13/14 and the expression of Snail2 (A-C) and Snail (D-F) in the prospective neural crest region was examined by whole mount ISH. Representative embryos are shown (anterior view, dorsal up, injected side right). Arrows indicate loss of expression of each marker on the injected side of xCdc4ΔFbox expressing embryos.