Supplementary Figure 6: Increasing cell confinement does not increase cortex tension and intracellular pressure in mitotic cells.

(a) Plot of cell radius and volume of STC arrested mitotic MYH9-GFP Lifeact mCherry expressing HeLa cells subjected to imposed confinement. The cells were confined to heights indicated (16 μm, n = 15 cells; 14 μm, n = 11 cells; 12 μm, n = 14 cells; 10 μm, n = 13 cells; 8 μm, n = 11 cells) and measured 60 seconds after confinement. (b) Quantification of cortex/cytoplasm ratio and cortical FWHM of F-actin (red) or myosin II (green). The cells were confined to heights indicated and measured 60 seconds after confinement. (c) Quantification of transient and persistent force (purple), pressure (grey) or tension (blue) of cells. The results show that with increased confinement the intracellular pressure and cortical tension decrease rather than increase. This decrease could be due to the increase in the surface area of the cell cortex upon confinement. Increase in cortex surface area would reduce the density of myosin motors in the cortex, which in turn could reduce cortex tension and intracellular pressure. The diamond-box contains 25–75% percentiles of the data and the bar denotes the median. Mann–Whitney significance tests of mitotic cells with respect to data plotted in the first column are indicated: (NS) U > 0.05, (^∗) 0.05 ≥ U > 0.005, (^∗∗) U ≤ 0.005.