Fig. 3. Cyclin E does not concentrate at centrosomes. L. pictus embryos (A. 40’, B. 50’, C. 60’, and D. 90’ after fertilization) were processed for double-label immunofluorescence microscopy using anti-cyclin E (A1-D1) and 4D2, a monoclonal antibody generated against sea urchin centrosomes (A2-D2). Merged images showing cyclin E (red) and 4D2 (green) are shown in panels A3-D3. Finally, embryos from the same batch were stained with 4D2 (red) and anti--tubulin (green) to demonstrate the activity of the centrosomes at these stages in the first cell cycle (A4-D4). There is no colocalization of anti-cyclin E and 4D2. Bar, 25 µm.