Figure 3: Forces generated by MDCK cells progressing through mitosis that are confined by micropillars.

Micropillar deflection and force generated by rounding mitotic MDCK cells increase from prophase to prometaphase until they reach maximum values in metaphase. In anaphase, micropillar deflection and, thus, the rounding force drops significantly. The generation of rounding force by mitotic MDCK cells was perturbed by the chemicals indicated. ‘Control’ indicates pillar deflection measured in absence of any chemical perturbation and ‘free micropillars’ indicates pillar deflection in absence of cells (that is, experimental noise). Fluorescence images show overlaid signals recorded from eGFP-labelled histones (H2B-eGFP, green) and DiD-labelled micropillars (blue) and were taken at the times indicated. Time zero denotes nuclear envelope breakdown. Background of the graph is colored to indicate the time range in which an example cell progresses through prophase (P, green), prometaphase (yellow), metaphase (blue) and anaphase (pink). Micropillars had an average distance of 14.3 μm and length of 13.7 μm. For each condition, the average and s.e.m. of the micropillar deflection as measured for n=30 cells is given. Scale bar, 8 μm. Perturbants are described in Supplementary Table 1.