Fig. 3.

Gtpbp2 is required for ectopic axis induction by Wnt but not stabilized β-catenin. a-e Axis induction phenotypes. a, c Control or b, d-e Gtpbp2 morpholinos (25 ng) were injected into both ventral blastomeres at the 4 cell stage, and mRNAs encoding (a-c), Wnt8 (4 pg) or d-e ptBcat (25 pg) were injected into a single ventral vegetal blastomere at the 8–16 cell stage. The Gtpbp2 morpholino blocks induction of secondary axes from Xenopus Wnt8 but not by a phospho-resistant form of β − catenin (ptBcat). e Coinjection of Gtpbp2 morpholino along with morpholino-resistant gtpbp2 mRNA (1 ng) restored secondary axes in Wnt-injected embryos. f Counts of total injected phenotypes, including intermediate Wnt phenotypes (partial secondary axis or enlarged head). g Diagram showing epistatic relationships between Wnt pathway reagents analyzed here and in Fig. 4