Fig. 8. Effects of Xror2 on activin-induced elongation of animal caps can be cancelled by Cdc42^T17N, a dominant-negative Cdc42 mutant. mRNA injection and animal cap assay were performed as described in Fig. 7. All animal caps were treated with activin A. (A) Xror2 inhibits elongation of animal caps by activin. (B) Co-expression of Cdc42^T17N with Xror2 partially rescues the extent of explant elongation. (C) Xwnt11 inhibits elongation of animal caps. (D) Co-expression of Cdc42^T17N with Xwnt11 partially rescues explant elongation. (E) Globin-expressing animal caps (negative control) treated with activin show elongation. Amounts of mRNA (ng/embryo):Xwnt11, 0.5; Cdc42^T17N, 0.6; Xror2, 0.2; globin, 1. (F) Summary of activin-induced elongation assay. The extent of animal cap elongation induced by activin (A-E) was classified by blind scoring as follows. -, no elongation; +, weak elongation; ++ moderate elongation; +++, strong elongation.