An Nkx2-5/Bmp2/Smad1 negative feedback loop controls heart progenitor specification and proliferation. by Prall, O, Menon, M, Solloway, M, Watanabe, Y, Zaffran, S, Bajolle, F, Biben, C, McBride, J, Robertson, B, Chaulet, H, Stennard, F, Wise, N, Schaft, D, Wolstein, O, Furtado, M, Shiratori, H, Chien, K, Hamada, H, Black, B, Saga, Y, Robertson, E, Buckingham, M, Harvey, R