Cortical contractility facilitates centrosome clustering in cells that do not express E-cadherin. (A, top) Schematic representation of AFM experiment. (Bottom) Bright-field images of chosen metaphase cells used for the stiffness measurements. Cantilever can also be observed in these images. Bar, 20 µM. (B) Quantification of apparent elasticity (Pa) in metaphase cells treated with blebbistatin (50 µM, 4 h) and calyculin A (1 µM, 2 h). (C) Quantification of apparent elasticity (Pa) in metaphase cells within a monolayer. (D) Immunofluorescence images depicting examples of bipolar clustered and multipolar telophases. Cells were stained for microtubules (α-Tub, red), centrioles (centrin2, green), and DNA (blue). Bar, 10 µM. (Inset) High magnification of centrioles. Bar, 1 µM. (E) Quantification of centrosome clustering in telophase upon blebbistatin treatment (50 µM, 4 h; n = 150). (F) Quantification of centrosome clustering in cytokinesis upon treatment with calyculin A (1 µM, 2 h; n = 150). For all graphics, error bars represent mean ± SD from three independent experiments. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, not significant.