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Figure S4. Microinjected actin monomers are less efficiently incorporated at the cell periphery without cell stimulation. COS7 cells were cotransfected with YFP-actin and LIMK1(WT) (A) or LIMK1(D460A) (B). MCF-7 cells were cotransfected with YFP-actin and cofilin/ADF siRNA (C) or control siRNA (D). Cells were microinjected with 24 µM Alexa546-actin monomers, without cell stimulation. Immediately after injection, fluorescence images for Alexa546-actin and YFP-actin were acquired every 30 s for 9.5 min at 30°C using fluorescence microscopy. Merged images of Alexa546-actin (red) and YFP-actin (green) are shown in the bottom panels. Fluorescence intensity of Alexa546-actin at the edge of unstimulated cells (arrows) was lower than that in the EGF- or NRG-stimulated cells (Fig. 8). See also Videos 7 B, 8 B, 9 B and 10 B. Bar, 20 µm.