Regulation of the positions of microtubule mini-asters and Golgi fragments. (A) Graphs representing the size of the microtubule network in cells (left) and cytoplasts (right) in response to drug treatments: 6 h treatment of Nocodazole (6 µM) in parallel to Y27632 (1, 20, or 30 µM) or Cytochalasin D (0.5 µg/ml) to generate small microtubule asters in strongly contractile (NZ 6/Y27632 1, n = 41), poorly contractile (NZ 6/Y27632 30, n = 40), or disrupted actin networks (NZ 6/CytoD 0.5, n = 44). The size of the microtubule network was defined as the projected area occupied by the microtubule network (see the dedicated section inside the Materials and methods). (B) Graphs representing the spreading area of the cells (left) and cytoplasts (right) in response to drug treatments. The spreading area was determined using the actin signal. (C) Representative fixed images of the dispersion of Golgi fragments in various actin contexts. From left to right: clustered Golgi fragments in a strongly contractile actomyosin context (NZ 6 µM/Y27632 1 µM), wider dispersion of Golgi fragments in a poorly contractile actomyosin context (NZ 6 µM/Y27632 30 µM), and broad dispersion of Golgi fragments spanning the entire cytoplasm in a disrupted actin context (Nocodazole 6 µM/Cytochalasin D 0.5 µg/ml). All images are max projections, further processed using an unsharp mask and a gamma filter. (D) Quantifications of Golgi apparatus dispersal in conditions leading to mini-asters of microtubules. Top graph shows the distance of the Golgi fragments to the centroid normalized by cell size (square root of the area of the cell) in the various actin contexts. The bottom graph shows the frequency distributions of the distance of the Golgi fragments to the centroid relative to cell size (bottom). “NZ 6/Y27 1”: n = 3,130 fragments, “NZ 6/Y27 30”: n = 3,248 fragments, “NZ 6/Cyto D 0.5”: n = 4,522 fragments. (E) The top graphs show the distance of the centrosome and the Golgi fragments to the centroid relative to cell size in response to the various drug treatments. The bottom graphs show the frequency distributions of the distance of the centrosome and the Golgi fragments to the centroid relative to cell size in response to the various drug treatments. In all graphs, horizontal bars represent the mean. P represents the P values, which were obtained from Kruskal–Wallis non-parametric tests (A, B, and D) or Mann–Whitney non-parametric tests (E).