Fig. 5. Entry into nuclei is required for SoxB1 degradation in macromere progeny, but not in primary mesenchyme cells. The assay was performed as described in the legend to Fig. 3. (A) SoxB1-GFP from which the DNA-binding domain and flanking NLS sequences were removed was cleared from micromere derivatives, but not from macromere progeny. (B) SoxB1 deleted of the DNA-binding domain but retaining the NLS sequences is preferentially degraded in both micromere and macromere progeny. (C) SoxB1-GFP deleted of the DNA-binding domain and 5'NLS sequence, but retaining the 3'NLS sequence. The arrows indicate clusters of ingressed primary mesenchyme cells. Scale bar: 20 µm.