One mechanism for the activity of this combination is that cisplatin inhibits the incorporation of exogenous L-methionine into cancer cells and increases the level of reduced folates, which are essential cofactors for the formation of a tight ternary complex of thymidylate synthase and 5-fluoro-2′-deoxyuridine-5′-monophosphatase. This evidence concerns the gene TYMS and cancer.