Figure 5.

XTC cell response to FCS and comparison to model. (A) Montages of leading edge of cell expressing p41-EGFP and LifeAct-mCherry stimulated by FCS at 200 s. The cell had been plated for 4 h. Intensity increases are evident after stimulation. Bar: 5 μm. (B) Intensities of p41-EGFP and LifeAct-mCherry averaged over all angles versus time. (C) Results of model showing concentrations of the free barbed end and F-actin concentrations, averaged over arc length. Rate constants were functions of time: r₀(t) = 1 μM s⁻¹ + 24 μM s⁻¹H(t), r₂(t) = 1 μM⁻¹ s⁻¹ + 624 μM⁻¹ s⁻¹H(t). Here H(t) = Θ(t – 250 s)t³/(T³ + t³), where T = 220 s and Θ is the step function.