Fig. 8. Wnt and Bmp signaling act cooperatively to regulate brachyury expression. (A) ES cells were differentiated in SRM and the indicated concentration of Bmp4 and Dkk1. RNA was prepared at day 3.5 and analyzed by RT-PCR for brachyury and Gapdh expression. (B) A2lox.sßcat ES cells were differentiated in SRM alone or SRM plus the indicated concentration of Bmp4 and/or doxycycline. RNA was prepared at day 3.5 and analyzed by RT-PCR for brachyury, Nodal and Gapdh expression.