Linker C , De Almeida I , Papanayotou C , Stower M , Sabado V , Ghorani E , Streit A , Mayor R , Stern CD .

GM60156 NIGMS NIH HHS , Biotechnology and Biological Sciences Research Council , Medical Research Council , R01 MH060156-01 NIMH NIH HHS, R01 MH060156-02 NIMH NIH HHS, R01 MH060156-03 NIMH NIH HHS, R01 MH060156-04 NIMH NIH HHS, R01 MH060156-05 NIMH NIH HHS, R01 MH060156-06 NIMH NIH HHS, BB/D010659/1 Biotechnology and Biological Sciences Research Council , G0400559 Medical Research Council , BB_BB/D010659/1 Biotechnology and Biological Sciences Research Council , MRC_G0400559 Medical Research Council

	Fig. 3. BMP inhibition together with eFGF activation induces neural marker expression indirectly in Xenopus. (A–L) Inhibition of BMP by injection of Smad6 into the A4 blastomere does not induce either Sox3 (A, B) or Sox2 (C, D) expression. eFGF together with BMP inhibition into the A4 blastomere induces Sox3 (E, F, N) and Sox2 (G, H, O). Neural induction by the former combination is inhibited when Nodal signaling is blocked: injection of Smad6 + eFGF together with CerS no longer induces Sox3 (I, J) or Sox2 (K, L). (M) Quantification of Sox3 and Sox2 expression in the different experiments described above. A, C, E, G, I and K dorsal views. B, D, F, H, J and L ventral views of the embryos to their left. N and O are enlargements of the areas enclosed by a square in F and H, respectively.
	Fig. 4. BMP inhibition together with FGF8a does not induce neural marker expression in Xenopus. (A–B) Injection of FGF8a into one cell at the two-cell stage does not alter Brachyury expression at the gastrula stage (A) but does expand β-tubulin expression at the neurula stage (B); arrowheads indicate the injected side. (C–F) Injection of FGF8a into an A4 blastomere, alone (C, D) or in combination with the BMP inhibitor Smad6 (E, F) does not induce Sox3 expression in ventral epidermis. A: vegetal view; B, C and E are dorsal views; D and F are ventral views of the embryos to their left. Black squares show the area enlarged in the inset in panels D and F.
	Fig. 5. Only the border of the neural plate is sensitive to BMP inhibition in Xenopus. (A–I) Smad6 (1 ng) injection into the A4 blastomere induces Pax3 (A–C), Slug (D–F) and Hairy2A (G–I). (A, D, and G: dorsal view; B, C, E, F, H and I: ventral view of the embryo to their left). (J–N) Injection into blastomere A2/3 expands Sox3 (J–L) and Slug (M, N). J, M: dorsal view; K, L and N are lateral views of the embryos to their left. White brackets in J show the extension of the neural plate in the injected and non-injected sides of the embryo. The black square in K indicates the area enlarged in L. Black arrows in L point to injected cells adjacent to the endogenous neural plate, expressing Sox3; the blue arrows point to injected cells distant from the endogenous neural plate, which do not express Sox3. Injected cells were recognized by FDX or LacZ (C, F, I, K, L and N, for embryos to their left). (O–P) Animal caps from Smad6-injected embryos at the 2-cell stage express Sox3 (O), which is not inhibited by CerS (P).

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