FIGURE 4.
Cell elongation induces cell softening and stress fiber alignment, but does not affect nuclear volume or DNA synthesis. (A) F-actin immunofluorescence image (upper) and AFM deflection image (lower) of 2500-μm2 representative spread elongated elliptic cells. Scale bar, 10 μm. (B) Stress fiber orientation evaluated at the cell periphery for 2500-μm2-spread circular and elliptic cells. The drawings show the stress fiber orientation corresponding to 0° in the graphs. For a given angle range, the orientation distribution function can vary from 1 (all fibers aligned along that angle range) to 0 (no fibers aligned along that angle range). (C) Comparison of G′, apparent F-actin content, nuclear volume of cells in G1, and DNA synthesis between nonelongated cells (solid bars) and elongated cells (open bars) for 900-μm2 and 2500-μm2 spreading. Data are presented as mean ± SE. *, p < 0.05; **, p < 0.01; and ***, p < 0.001.