Centrosomes comprise two centrioles that are surrounded by pericentriolar material (PCM). The PCM increases in size during mitosis, as centrioles recruit new PCM from the cytosol — a process known as centrosome maturation. Raff and colleagues studied PCM assembly in mitotic centrosomes of Drosophila melanogaster embryos. Using photoactivation and three-dimensional-structured illumination super-resolution microscopy, they found that Centrosomin (Cnn) is incorporated into the PCM at the centrosome centre and then moves towards the periphery, where it detaches from the PCM. In this way, Cnn forms a scaffold-like structure that emanates from centrioles. Centrosome-specific phosphorylation of Cnn by Plk1 (Polo-like kinase 1) was required for this outward movement and for centrosome maturation. This suggests a model in which a Cnn scaffold assembles at the onset of mitosis, when Plk1 is activate, to recruit other PCM proteins.