Fig 2. Ectopic Tbx2 suppresses mesendoderm induction.

(A) Tbx2 inhibits Activin-induced mesendoderm. RT-PCR analysis of animal cap explants dissected at late blastula stages and cultured until midgastrula stages. Activin (0.25ng/ml) was added to stage 8 animal caps excised from uninjected embryos or from embryos injected with tbx2 RNA into the animal pole of both blastomeres at the two-cell stage. (B) Inhibition of FGF-mediated mesoderm induction by Tbx2. RT-PCR analysis of animal cap explants dissected at late blastula stages and cultured until midgastrula stages. bFGF (10ng/ml) was added to stage 8 animal caps excised from uninjected embryos or from embryos injected with tbx2 RNA, as listed. Unless otherwise noted, 1ng of tbx2 RNA was used in this and in subsequent experiments.