Fig. 2.
Analysis of the initial response time. (A) Sample kymograph of the mathematical model simulation under graded Rac stimulation. (B) Model response time vs. normalized gradient (s1) for two different values of so (input). (C–E) Kymographs chronicle typical changes in cell morphology seen during early time periods. The first image before each kymograph depicts the gradient (red) that the cell is experiencing as visualized with Alexa 594 dye. The gradient is not shown in resulting images to promote clarity of morphological changes. The green color indicates expression of YF-TIAM1. Red dotted lines highlight evolving cell boundaries. Yellow arrowheads indicate initial polarities. Times are given in minutes. (Scale bars, 10 μm.) (F) Dependence of initial response times on gradient values. States are color-coded: state I, green (n = 29); state II, blue (n = 37); and state III, red (n = 27). In each plot, the colored dots highlight the dependence of that particular state and the gray dots illustrate where the response times of the other states fall. Data are fitted based on simulation results. Spearman correlation coefficient: state I = −0.679, state II = −0.655, and state III = −0.583. Τhe asterisk indicates a statistically significant difference (state II vs. state I, P < 1e-4; state II vs. state III, P < 1e-3) between the state II curve vs. the other states. There is no statistical difference between state I and state III (P = 0.54). Both tests were carried out using an F test.