mdk2 activity affects emx1 expression pattern in the anterior forebrain and hoxC10 expression in the posterior CNS. (A–D) Lateral views of emx1 expression (arrow) in the telencephalon and hoxc10 expression (arrowhead) in the tail bud of a control embryo (A) and embryos injected with 150 pg RNA encoding mdk2 (B, C) and with 500 pg RNA encoding dominant-negative mdkΔ38 (D). Note reduction (B) or complete repression (C) of emx1 expression (arrows) and expansion of hoxC10 (C, arrowhead) in mdk2-injected embryos. On the other hand, emx1 expression (arrow) appears caudally expanded in mdkΔ38-injected embryos (D). (E–L) Higher magnification of head regions (E–H lateral views, I–L dorsal views, anterior to the left). The emx1 expression domain is shortened (F, J) and dislocates ventrally (F) or is completely missing (G, K) in mdk2-injected embryos compared to control embryos (E, I), while it extends caudally in mdkΔ38-injected embryos (H, L). (M–P) Dorsal views of hoxC10 expression in the tail bud. hoxC10 is upregulated in mdk2-injected embryos (O, compare to control embryo in M), but is not significantly affected in mdkΔ38-injected embryos (P). Note that the mdkΔ38-injected embryo in P is at a slightly earlier stage (12 hpf compared to 14 hpf for control and mdk2-injected embryos), which accounts for the apparently weaker hoxC10 staining.