Fig. 4.

Dominant negative (DN) Rho but not DN-Rac prevents the hypertonicity-induced phosphorylation of cof. Cells were transfected with Myc-tagged DN-Rho (A) or DN-Rac (B) constructs, as described under Fig. 3, treated iso- or hypertonically (as indicated), and stained for phospho-cofilin (pcof, red) and the Myc epitope (green). The presence of cells was visualized by the nuclear stain 4,6-diamidino-2-phenylindole (DAPI) (blue). To help identification of the transfected cells on the red image, the area of the corresponding cell(s) was traced with a dashed line. Note that the expressions of DN-Rho almost completely suppressed the hyperosmolarity-triggered increase in pcof staining, whereas the pcof content of DN-Rac-expressing cells is indistinguishable from their nontransfected neighbors. In DN-Rho expressors, we occasionally observed some pcof labeling in nuclear/perinuclear areas.