Figure 3.

Dynamics of B-50/EGFP–induced filopodial extensions in living Rat-1 fibroblasts. Rat-1 fibroblasts were transfected as described in the legend to Figure 2. Upon trypsinization, cells were replated on 24-mm glass coverslips, mounted in a microchamber, and transferred to the microscopic stage of the confocal microscope where they were kept at 37°C and 7% CO₂. Upper frames show GFP-fluorescence in pB-50/GFP-transfected cells; lower frames show the corresponding phase contrast images. (a) Frames at selected timepoints after replating showing the spontaneous extrusion of long, stable, substrate-attached filopodia in a pB-50/EGFP–transfected cell. (b) Time lapse sequence of a pB-50/EGFP–transfected cell showing the transition from a filopodial to a ruffled or lamellar phenotype. Note that untransfected cells do not show a filopodial phenotype preceding lamellar spreading. Scale bar, 10 μm.