The invention provides compositions for inhibiting a redox-sensitive GTPase protein, including a Rho or Rab family GTPase, comprising an effective amount of a redox-sensitive purine compound and an effective amount of a redox agent. The invention further provides methods of inhibiting a redox-sensitive GTPase protein, including a Rho or Rab family GTPase, by administering compositions of the invention. Methods of screening for compounds that inhibit a redox-sensitive GTPase protein, including compounds that target and inhibit Rho or Rab family GTPases, are further provided.
