Rock signaling acts downstream of bone morphogenetic protein (BMP)/noggin. (A-F) Neural primordia explanted after in ovo electroporation with control green fluorescent protein (GFP) (A,D), noggin/GFP (B,E), or noggin/GFP and Y27632 (C,F). While noggin inhibited delamination and augmented formation of stress fibers, Y27632 rescued both processes. (A-C) Merged GFP immunofluorescence and phase contrast. (D-F) Phalloidin staining showing enhancement or loss of stress fibers upon noggin or noggin+Y27632 treatments, respectively. Inset in (F) shows morphology of transfected cells (arrowheads). (G-I) Treatment of NT explants with lysophosphatidic acid (LPA) prevents neural crest (NC) delamination and maintains membrane-bound N-cadherin (green) (G). Replacing LPA by BMP4 reverts cell delamination and downregulates N-cadherin (H). In contrast, in the continuous presence of LPA, BMP4 is unable to rescue NC emigration or N-cadherin loss from the cell membranes (I). Bar: 80 μM (A-C); 4 μM (D-F); 8 μM, inset in (F); 42 μM (G-I).