s-FDAP analysis. (A) Procedures of s-FDAP analysis. Dp-actin expressed in MCF-7 cells was prebleached to the background level. s-FDAP analysis consists of DIC image acquisition, photobleaching of the whole cell, photoactivation of the 1.8-µm-diameter region (solid circle), and fluorescence image acquisition of a rectangular region (white box) before and at 0 and 40 ms after photoactivation. The fluorescence intensities in the 3-µm-diameter region (dashed circle) before (blue) and at 0 (green) and 40 ms (red) after photoactivation were measured. Each set of procedures was repeated 84 times at 10-s intervals. Bars, 20 µm. (B) Time course of fluorescence intensities measured as in A. (C) Time course of relative FDAP from the data shown in B. FDAP values are expressed as the difference between fluorescence intensities 0 and 40 ms after photoactivation and are normalized to the mean FDAP value during the first 2-min observation.