Schematic illustration of the first dynamic assay: sequential addition of tubulin followed by tubulin and actin on isolated centrosomes. Representative images showing microtubules (top line) and the merged images of actin and microtubules (bottom line) for the two steps of the assay; in the presence of tubulin only (left column) and in the presence of tubulin and actin (right column). Scale bar: 10 µm. Quantification of the differences in the number of microtubules per centrosome between the two stages of the experiment described above on centrosomes capable (first condition), or not (second condition), to grow actin filaments. Data were collected from a single experiment; asters without actin filaments: n= 29; asters with actin filaments: n= 13. Data were analyzed using Mann-Whitney test. 