Fig. 2. (A) Tbx5/Tbx4 expression in cultured explants. Lateral tissues at the level of the presumptive wing and leg regions were prepared from embryos at stages 9 to 14. After incubation for 24 hours, RT-PCR and Southern blot analysis with Tbx5 or Tbx4 probes were performed. The relative amount of each gene was plotted (B,C) after being standardized with ß-actin. The gene expression in stage 9 non-cultured explants was taken as 1.0 for a control. Each experiment was repeated 5 times. Error bars indicate standard deviation.