Abstract: The present invention is directed to methods and compositions regarding induction of apoptosis in a cell and treatment of cancer in an individual wherein methionine deprivation of the cell is followed by methionine repletion of the cell. The methionine deprivation of the cell results in G2 arrest in the cell, leading to DNA damage in the cell. Upon readministration of methionine to the cell, the damaged cell exits G2 arrest and enters into apoptosis. In a specific embodiment, a therapeutic effect is elicited by cycling the patient between a methionine-depleted diet and a normal, methionine-replete diet. The present invention also regards chronic methionine deprivation for treatment of cancer in a human, in addition to methods for methionine restriction as adjunctive therapy for other cancer treatment methods.