Fig. 4. Indirect induction of Chordin by Xnr1 and ß-catenin. Induction of Chordin by ß-catenin (A) and by Xnr1 (B) is inhibited by cycloheximide. RNA (100 pg) encoding Xnr1 or constitutively active ß-catenin was injected into Xenopus laevis embryos at the one-cell stage and animal caps were dissected at mid blastula stage 8 (before the mid blastula transition). The animal pole regions were allowed to develop for 3 hours in the presence or absence of cycloheximide and RNA was analysed by quantitative RT-PCR for expression of Chordin. Induction of Chordin by both Xnr1 and ß-catenin is inhibited by cycloheximide and is therefore indirect.