Fig. 4

Fig. 4 osr1 is a direct target of Nodal signaling. A–D: Animal pole view. A′–D′: Lateral view, dorsal to the right. Embryos (4 hpf) were injected with 2 ng recombinant mouse Nodal protein (B, B′) or 400 ng BSA (A, A′). Half of the injected embryos were treated with 50 µg/ml cycloheximide (C, C′, D, D′), and all were fixed after 1 hr and 20 min. Nodal protein strongly induces ectopic osr1 expression in the animal pole of the embryo (B, B′). Ectopic expression is induced in the presence of cycloheximide indicating that osr1 is a direct target of Nodal signaling (D, D′).