Figure 4.

Eng-Sia inhibits axis induction by the wnt pathway. At the four-cell stage, one ventral blastomere was injected with 30 pg of β-galactosidase (A–F) or Eng-Sia (G–L) in combination with 5 pg of Xwnt8 (B, H), 1 ng of β-catenin (C, I), 30 pg of siamois (D, J), 200 pg of noggin (E, K), or 200 pg of chordin (F, L) mRNA. Axis induction was observed in response to Xwnt8, β-catenin, siamois, noggin, and chordin. Eng-Sia blocked axis induction by Xwnt8, β-catenin, and siamois but not by noggin and chordin. Neither β-galactosidase nor Eng-Sia induced axis formation. See Table 4 for quantitation. In a parallel experiment, dorsal injection of Eng-Sia inhibited axis formation (data not shown).