Fig. 4.

Sox9 phosphorylation is required for cooperating with Snail2 to induce an EMT. (A) Embryos transfected with Sox9/Snail2; SOX9^S64D,S181D/Snail2; SOX9^{K61R,K254R,K376R}/Snail2 result in NC delamination in the intermediate and ventral extent of the neural tube where expression of basal laminin and apical PKC are lost (white arrows). However, most of the Sox9^S64A,S181A/Snail2-transfected cells remain in the neuroepithelium without disrupting basal laminin and apical PKC expression. (B) The amount of Snail2 protein presence in the IP fraction of Sox9^{K61R,K254R,K376R} transfected embryos is less than that of WT-Sox9. No Snail2 protein is detected in the IP fraction of Sox9^S64A,S181A-transfected embryos. (C) Schematic of WT-Sox9 or Sox9^S64A,S181A-Snail2 tethered construct. Horizontal white line in the Insets indicate the plane of sectioning of the transfected neural tube with WT-Sox9-Snail2 or Sox9^S64A,S181A-Snail2. Both tethered constructs can induce ectopic HNK-1 expression. Cells expressing Sox9-Snail2 emigrate from the dorsal, medial, and ventral extent of the neural tube (yellow arrows) with loss of basal laminin and aPKC expression. In contrast, the majority of Sox9^S64A,S181A-Snail2-expressing cells remain in the neuroepithelium without disrupting laminin and aPKC expression. (Scale bars, 100 µm.)