A. Effect of dominant negative mutant of Rac1 T17N on localisation of Arp2/3 complex in cell spreading. MEFs were transfected with myc tagged T17N Rac 1 and spread for 60 minutes on fibronectin. Scale bar 10 μm. Inset 2 μm B, C. Effect of constitutively active mutant of Rac 1 Q61L on localisation of Arp2/3 complex in cell spreading. Scale bar 10 μm. Inset 10 μm B. Polyhedral morphology C. Radial morphology. Actin was labelled with rhodamine phalloidin and Arp2/3 complex with an antibody to the p34-Arc subunit. Expressing cells were identified by labelling with an antibody to myc (not shown).