Subcellular localization of endogenous Rac1. Lin⁻/c-kit⁺ cells were stimulated with SDF-1α (100 ng/mL) for indicated times, fixed, and then stained with anti-Rac1 mAb (green), rhodamine-labeled phalloidin (red), and 4′,6-diamidino-2-phenylindole (blue). The leading edges are indicated with a white arrow. The representative images from 3 independent experiments are shown.