MEK1 and MEK2 have key roles in tumorigenesis and, therefore, represent promising targets for cancer therapy; however, MEK1/2 inhibitors have been shown to have efficacy in only a narrow range of cancer types, mainly tumours that harbourBRAF or NRASmutations. In this article, the clinical experience with MEK inhibitors to date is reviewed, and potential approaches to overcoming therapeutic resistance and increasing the efficacy of treatment are discussed.
