Fig. 2. Analysis of the elongation of integrin clusters at FCs. (A) A composite TIRF image of 12 cells with superimposed arrows that indicates the direction of elongation of the integrin clusters. Each TIRF image was taken from a region of the cell where active elongation of integrin clusters at FCs was seen. Each arrow shows the gross shape and length of a cluster analyzed and the direction of its elongation. The brightness of the arrow indicates the elongation rate (ER) of the cluster. For example, white arrows show the FCs that elongated with a rate greater than 0.4 µm minute-1 and black arrows a slower elongation rate (<0.2 µm minute-1). (B) Time courses of elongation of integrin clusters at FCs located at the marginal and central regions of the cells. The elongation rate at the marginal region was significantly higher than that in the central region at 12 minutes and 15 minutes. (C) The relative direction (
) of the elongation was measured with respect to the horizontal axis that approximates a tangent to the cell margin nearest to the cluster. (D) Histogram of the direction distribution of the elongation. Each bar indicates the numbers of elongating clusters with different directions () defined in (C).
