PAPC function beyond PCP inhibition is required for cleft formation. (A) Quantitation of separation in gain-of-function experiment. BCR was injected as indicated. (B–D) Ectopic cleft formation in the BCR, as in Fig. 3 (G–L). (E) Exemplary kymographs of cleft contact formation, as in Fig. 4 E. (F) Frequency of cleft contacts after reaggregation, as in Fig. 4 C. (G) Reduced Dvl-GFP puncta in EphB4-MO–injected mesoderm (green) at boundary to BCR (red, membrane-RFP in ectoderm). (H) Quantitation of separation behavior. (left) Mesoderm injected as indicated was tested on normal BCR. (right) BCR explants injected as indicated were tested on normal BCR. (I) Model of tissue separation at the mesoderm–ectoderm (BCR) boundary.