Subject: I dont know how to solve a problem like this???

I am in intro to Biochem and my professor gave me this problem for extra 
credit, and I really have no idea even where to begin on this. I've tried to 
find answers everywhere so I figured I try you:

Your patient has a benign tumor of his Schwann cells, and and altered protein. 
An Experiment, in which you incubate the protein p21ras with this protein and 
measure what percentage of the guanine nucleotide bound to the p21ras is GTP, 
shows:
Protein                          GTP/(GTP+GDP) on p21ras(%)
Your patient's protein                      50
Normal protein                               5
a. What is the role of the protein that appears to be defective in you 
patient? How could the mutation cause the observed problem?
b. Why might an inhibitor of farnesyltransferase help this disease?

Re: I dont know how to solve a problem like this???