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Fig. 3
Glypican 4 regulates Rac1 activity in migratory endodermal cells. (A) Schematic diagram illustrating the endoderm transplantation procedure. Donor embryos obtained from crossing gpc4 heterozygous fish were injected with sox32 and PDB-GFP RNAs plus rhodamine-dextran (a marker of cell volume) at the one-cell stage. At the blastula stage, 30-50 donor cells were transplanted into host embryos obtained from crossing gpc4 heterozygous fish. (B-C″) Confocal time-lapse analysis of endodermal cells expressing (B,C) PDB-GFP, a fluorescent Rac1 probe, and (B′,C′) dextran. Rac activity was determined as the ratio of the PDB-GFP:dextran signals, and is displayed as radiometric pseudocolored images (B″,C″). Yellow indicates a higher value of PBD relative to dextran. White arrows indicate the direction of migration of endodermal cells (Movie 3). (D) The mean ratio of PDB-GFP:dextran in indicated embryos. The numbers of embryos and cells analyzed are shown. ****P<0.0001; Student's t-test.