Figure 3.

Force-induced cell deformation by magnetite beads. (A) A7 and M2 cells were incubated with collagen-coated magnetite beads, subjected to mechanical force by placing a permanent magnet at different distances from the culture dish surface, and analyzed by confocal microscopy. Attached beads are indicated by arrowheads. (B) Deformation of cells treated as described in A was measured using a confocal scanning laser microscope by obtaining a z-stack series of images of the untreated and force-treated cells. Cell height is calculated as the difference between the exact Z-position of the start point and the end point of the phalloidin-stained dorsal cell membrane. At least 10 cells were assessed in each sample. (C) A7 and M2 cells were treated as described in A. Cell extracts were then incubated with GST-PBD immobilized on glutathione-Sepharose beads, and the amounts of Rac in cell lysates before pull-down and GST-PBD–bound Rac were detected by immunoblot. (D) Intensities of bands were measured using ImageJ densitometry software. Numbers represent ratio relative to the levels of Rac in cell lysates before pull-down and are expressed as the means and SDs of three independent experiments. *p < 0.01 versus respective untreated control.