Figure 1.

The cdk inhibitor p21 blocks centrosome duplication in frog embryos. Embryonic cells were injected with various inhibitors and treated with cycloheximide for 4 h to allow for centrosome overduplication. Asterisks mark the injected cells, as visualized by coinjection of a fluorescein-conjugated dextran. (A) p21. (B and B′) p21 and cyclin E (two different sections are shown to view all centrosomes). (C) p21 N terminus. (D) p21 C terminus. (A) γ-Tubulin staining. (B, B′, C, and D) α-Tubulin staining. The difference in cell size is because of the variation in cell stage at the time of injection. (Bar = 100 μm.)