Figure 2.

Cytomechanical response of Swiss 3T3 cells to Rho activation. (A) Mean cellular compliance directly computed from the mean-squared displacements of the thermal motions of microspheres injected into the cytoplasm of serum-starved Swiss 3T3 cells before (red) and 15 min after (blue) treatment with 1 μg/ml LPA. Error bars denote SE of measurement. Inset, mean cellular compliance of the cytoplasm of serum-starved Swiss 3T3 cells injected with 10 μg/ml C3, before (red) and after (blue) treatment with 1 μg/ml LPA. (B) Frequency-dependent viscous and elastic moduli, G″(ω) and G′(ω), obtained from mean cellular compliances (A). G′(ω) is represented by circles and G″(ω) by squares. (C) Frequency-dependent phase angle, δ = arctan (G″/G′), calculated from viscoelastic moduli (B). (D) Shear viscosity obtained from the product of the plateau modulus and relaxation time (B).