FIG. 4.

Microinjection of Ras^V12, Ras^S35, and Ras^G37 proteins stimulates DNA synthesis. Quiescent cells were injected with Ras^S35 or Ras^G37 (0.5 mg/ml, the minimal active concentration in these cells) and labeled with BrdU for 48 h. BrdU incorporation in IgG-injected cells is shown as a negative control. (Inset) BrdU incorporation following injection of Ras^V12, Ras^S35, and Ras^G37 at similar concentrations (0.075, 0.1, and 0.1 mg/ml, respectively). C, IgG-injected cells. Error bars indicate 95% confidence intervals based on the standard error of proportion. The absence of an error bar indicates a standard error of proportion of 1 or less. More than four independent preparations of the Ras proteins were tested with similar results.