Fig. 1. FGF activates the Xral protein. Animal caps explanted from post-MBT embryos (stage 9) were cultured for 4 hours in the presence (+) or absence (–) of 100 ng/ml bFGF (A) and analysed by RT-PCR for Xbra expression (B) or by immunoblotting to detect the GTP form of Xral (C). Active Ral-GTP was affinity purified from lysates of 15 animal caps (C) using the Ral-binding domain of RalBP1, and detected with anti-Ral antibodies. The result is representative from two separate experiments.