Fig. 2

Tbx2 associates with R-Smads a). Tbx2 physically associates with Smad1. 1 ng myc-tbx2 RNA was injected at early cleavage stages. Pull-down of native Smad1 from injected embryos leads to co-immunoprecipitation of exogenous Tbx2. Normal rabbit IgG antibodies were used in parallel studies as a negative control. b Tbx2 physically associates with Smad2. 1 ng of myc-tbx2 and 1 ng of flag-smad2 were injected at early cleavage stages. Pull-down of Flag-Smad2 from injected embryos leads to co-immunoprecipitation of exogenous Tbx2. Normal rabbit IgG antibodies were used in parallel studies as a negative control c) Tbx2 represses Smad2-mediated mesoderm induction. Embryos were injected with tbx2 (1 ng), flag-smad2 (1 ng), or tbx2 (1 ng) and flag-smad2 (1 ng) at the two-cell stage and animal caps were explanted at stage 8.5. d Tbx2 physically associates with Smad4. 1 ng of myc-tbx2 and 1 ng of flag-smad4 were injected at early cleavage stages. Pull-down of Flag-Smad4 from injected embryos leads to co-immunoprecipitation of of exogenous Tbx2. Normal rabbit IgG antibodies were used in parallel studies as a negative control