Figure 5.

R-Ras regulates cell polarity. T47D cells were plated on collagen-coated coverslips (3 μg/ml) for 45 min and then coimmunostained for p16, a component of the arp2/3 complex, and actin. The merge shows actin in green and p16 in red. Control cells localize p16 and a rich actin network to the leading edge. This is enhanced in cells expressing dominant negative R-Ras (41A) and diminished in cells expressing activated R-Ras (38V). Scale bar, 25 μm. One hundred cells from three individual experiments were counted, and p16 staining was scored as polar, nonpolar, or diffuse. The percent of polar cells ± SEM are graphed. Expression of activated R-Ras (38V) significantly (^*p < 0.05) decreases the number of polar cells, whereas expression of dominant negative R-Ras (41A) significantly (^**p < 0.05) increases the number of polar cells.