Fig. 3.

Mapping FGF inhibitory activity to the TSP domain. (A) Schematic of Rspo2 constructs Rspo2, RspoΔF and RspoΔT. (B-K) Four-cell embryos were injected with 0.5 ng Rspo2, RspoΔF or RspoΔT RNA each, as indicated, and cultured until stage 8. Ectoderm explants were dissected, treated with 100 ng/ml of FGF2 with or without SU5402 (100 µM, final concentration), and cultured until stage 13. (B-I) Explant morphology is shown for unstimulated explants (B-E) and FGF2-stimulated explants (F-I). (J,K) Effects of Rspo2 constructs on FGF-dependent Erk1 activation. Immunoblot analysis was carried out with the antibodies against pErk1 and total Erk1. Scale bar: 300 µm.