Time course of Cdc42 activation following SDF-1 stimulation. Cdc42 activation was studied after SDF-1 (100 ng/mL) activation of Lin^– cells from 129Sv and WASP-deficient mice by a pull-down assay. The GST-WASP-CRIB–binding domain was used to evaluate GTP-bound Cdc42 (upper panel). The immunoblot of total lysates by Cdc42 antibody is shown in the lower panel. The last line represents the pull-down and total Cdc42 lysates of transfected cells by a dominant activated Cdc42 (CDc42-Val12).