The graph shows the number of microtubules per centrosome in response to increasing concentrations of monomeric actin. Data were pooled from 2 independent experiments; 0 µM: n=21; 0.3 µM: n=17; 0.5 µM: n=17; 1.0 µM: n=17. ****:P<0.001 Mann-Whitney test. 