Fig. 4. Wnt5b signal regulates MyoD expression. (A,B) Rescue of the MyoD-inhibitory effect of S-Fz7 by Wnt5b co-injection. (A) MyoD expression in an embryo co-injected with S-Fz7 transfected cells mixed with control cells at a ratio of 1:5. Seventy-one percent of these embryos present an inhibition of MyoD expression (n=27/38). (B) Rescue of MyoD expression by co-injection of S-Fz7 transfected cells mixed with Wnt5b-expressing cells at a ratio of 1:5. In 57% of embryos, MyoD expression was rescued to normal levels (n=25/44). (C) Inhibition of MyoD initiation in DN-Wnt5b electroporated embryos. Mouse Wnt5b (red) and MyoD (blue) expression in embryos electroporated with DN-Wnt5b in the caudal neural tube. 80% of the embryos presented inhibition of MyoD initiation (n=15/18). (D) GFP (red) and MyoD (blue) expression in embryos electroporated with a GFP cDNA in the caudal neural tube. All of the embryos had normal MyoD expression (n=12).