Fig. 1.

Cell shape and volume changes upon detachment from the substrate. (A) In the adherent state, both actin filaments and microtubules apply forces on the nucleus. Upon cell detachment, actin stress fibers no longer surround the nucleus and become cortical. Addition of nocodazole removes microtubules. We independently perturb actin and microtubules using a combination of cell detachment and nocodazole (Noco) as illustrated in the schematic. (B) Confocal fluorescent images of a MEF transfected with GFP–lifeact. Upon mild trypsin treatment, the cell gradually detached from the substrate and its shape became more round. (C) Actin filaments (green) and microtubules (red) in an adhered cell. Microtubules surround the DAPI-stained nucleus (blue). This image is also shown as a control in Fig. 5A. (D) Actin filaments (green) and microtubules (red) in the suspended cell. Actin is cortical and microtubules surround the nucleus (blue). (E) Percentage reduction in MEF cell volume during the detachment from the substrate. The green line is fitted to the measured volume reduction over time (blue circles). The data are mean±s.e.m. obtained from 35 independent live cells (>10 cells per trial, repeated three times). Scale bars: 10 μm.