Cy3 labelled actin monomers incorporate into sites of Arp2/3 complex localisation in filopodia. Cells were spread for 60 minutes on fibronectin, permiabilised in the presence of Cy3 labelled actin and fixed. A. Incorporation of Cy3 actin to the cortex and nucleus of MEF spread for 60 minutes on fibronectin. Nuclear labelling has been reported previously with this assay  Scale bar 10 μm. B. Enlargement of boxed area in A. showing Cy3 actin incorporation into lamellipodia and cytoplasmic actin spots. Scale bar 5 μm. C. Cy3 actin incorporation into sites of Arp2/3 complex localisation in filopodia. Actin was labelled with rhodamine phalloidin and Arp2/3 complex with an antibody to the p34-Arc subunit. Scale bar 5 μm.