The present invention relates to a method of identifying compounds as candidate drugs for treatment of cancer by providing a cell expressing a GTPase protein that is regulated by a prenyl-electrostatic switch, contacting the cell with compounds to be evaluated, and selecting compounds able to regulate charge at the prenyl-electrostatic switch in the GTPase protein as candidate drugs for treatment of cancer. Also disclosed are methods of treating cancer in a patient. An isolated antibody which binds to a phosphorylated prenyl-electrostatic switch on a K-Ras4B protein is also disclosed, as is a kit for detecting phosphorylation of a prenyl-electrostatic switch in a K-Ras4B protein which includes a labeled antibody and a device to detect the label. Also disclosed is a method of detecting phosphorylation of a prenyl-electrostatic switch on a K-Ras4B protein in a biological sample.