Fig. 9. Constitutively active Rac overcomes the effect of the SH3 domain on cell spreading. BAE cells were transiently transfected with plasmid encoding EGFP-tagged SH3 domain alone or together with constitutively active Q61LRac. Cells were detached, washed and sorted. (A) Enriched populations of cells expressing EGFP-tagged SH3 domain alone were replated on fibronectin for 1 hour. (B) Enriched populations expressing SH3 domain together with constitutively active Q61LRac were replated on fibronectin for 20, 30, 45 minutes or 1 hour. Cells were fixed, permeabilized and stained with antibody against HA epitope to detect constitutively active Rac. Actin filaments were detected with TRITC-labeled phalloidin. Bar, 20 µm.