English: Supplementary Movie 3 Constitutively active ForA is excluded from nascent protrusions. Reconstituted forA- growth-phase cells expressing GFP-ForAΔDAD were imaged as above using 488 nm laser excitation. Fluorescence intensity distributions of 8-bit grey scale images are displayed in pseudo-colour. The spontaneous attempt to form a new front in the rear (white arrow head) - which in this case eventually failed - was associated with concomitant disappearance of the formin. This demonstrates that the formation of migratory protrusions and presence of the active formin are mutually exclusive. Time is min:s. Scale bar, 10 μm.