Fig. 1. XFast-3 is a novel member of the Fast family. (A) ARF2 is an ARE-binding complex distinct from the XFast-1-containing ARF1, which appears about 240 minutes post stage 8. Nuclear extracts prepared from uninjected embryos or embryos injected with 200 pg mRNA encoding activin-ßA at the times indicated were analysed by bandshift using the ARE as probe. ARF1 is only detected in activin-injected embryos; the faster mobility complex ARF2 is detected in uninjected embryos. (B) The sequence of XFast-3 aligned with the sequences of XFast-1, mouse Fast-2/FoxH1, human Fast-1/FoxH1 and zebrafish FoxH1 (Attisano et al., 2001). Grey underlining, forkhead/winged-helix DNA-binding domain (Kaufmann and Knöchel, 1996); broken line, the Fast motif (FM); unbroken black line, the Smad interaction motif (SIM) (Germain et al., 2000).