Fig. 6

Fig. 6  Alk4 S275M rescues marker gene expression in SB-431542-treated embryos. Zebrafish embryos were injected with 50 pg Alk4 S275M or 50 pg Alk4 WT and treated with 100 μM SB-431542 or DMSO at 16-cell stage. Embryos were harvested for in situ hybridization for gsc at shield stage (A–D, dorsal to the right), ntl at bud stage (E–H, anterior to the top), and shh at 18 somite stage (I–L). Alk4 S275M restores gsc expression in SB-431542-treated embryos (A), whereas Alk4 WT did not (C). Notochord expression of ntl at bud stage was restored in Alk4 S275M-injected embryos (arrow in panel E), but not in Alk4 WT embryos (G). Similarly, expression of shh, including anterior domains (arrows in panel I), was rescued in Alk4 S275M embryos (I), but not in Alk4 WT embryos (K). DMSO-treated embryos displayed normal expression patterns for all genes examined (B, D, F, H, J, L).