Figure 4.

R-Ras modulates protrusive activity during cell migration. Control cells protrude and retract, whereas cells expressing activated R-Ras (38V) show little protrusive activity. Cells expressing dominant negative R-Ras (41A) protrude continuously, consistent with the observed increased persistence. T47D cells were plated on collagen (3 μg/ml) for 1 h and then time-lapse microscopy sequences were acquired for 10 min, with one image collected every 3 s. A one pixel-wide line was drawn along a protrusion in order to generate a kymograph using Metamorph software (Bear et al., 2002). Fifty protrusions from two separate experiments were analyzed, per cell type, and protrusive velocity was then calculated as previously described (Bear et al., 2002), ^*p < 0.05 versus control. Scale bars: x, 2.5 min; y, 15 μm.