Fig. 2. Spry1 is induced by FGF8b-soaked beads in prosomere 1 explants in the absence of protein synthesis. Spry1 (A) and Spry2 (B) are expressed in broad domains of the mid/hindbrain region at E9.5 Spry1 is induced by FGF8b-soaked beads within 4 hours of culture (D), but not by BSA-soaked beads (C). (E-H) Spry1 is induced within 6 hours by FGF8 in the presence or absence of 50 µg/ml cyclohexamide (CHX) in explants grown in medium containing 0.1% ethanol, but not by BSA-soaked beads. Red arrows in D,F,H indicate induced gene expression. Green circles in C and H indicate beads that were lost during processing of the tissues. Broken lines in A and B indicate the tissues used for the explant assays.