Fig. 5. The actin-binding ability of SWAP-70 through the C-terminal region is crucial for membrane ruffling induced by dominant-active Rac. (A) COS7 cells were transfected with RFP-RacV12 together with GFP or GFP–SWAP-70(1-564). Localization of SWAP-70 (green) and Rac (red) was observed under the confocal microscope. Stacked images are indicated by `S', and dorsal planes of focus by `D'. Membrane ruffles (indicated by arrowheads) were observed in the cells that did not express GFP–SWAP-70(1-564), but not in those that expressed the protein. Bar, 20 µm. (B) Ruffling formation observed in the experiments illustrated in A was quantified by scores defined in the Materials and Methods (left panel). Formation of filopodia was monitored by similar analysis as in A by use of RFP-Cdc42V12 instead of RFP-RacV12 and quantified by scores defined in the Materials and Methods (right panel).