Figure 8.

RAS GTPase stimulation by neurofibromin domains. A, phosphate sensor assay using purified neurofibromin proteins. The level of stimulation of basal RAS GTPase activity is shown for four different neurofibromin proteins and an equimolar mixture of ABC and DEF proteins. Data shown are the averages of two separate assays, each performed in triplicate, with standard deviations shown with error bars. B, RAS–GTP ELISA carried out in HEK293 cells lacking endogenous NF1. The plotted data are measurements of RAS–GTP levels after EGF stimulation of serum-starved cells that were transfected with various NF1 constructs. Data are percentages of a control experiment with GFP and are averages of three or four replicate wells for each sample. Standard deviations are noted with error bars.