FBXW7 (F-box/WD repeat-containing protein 7) is part of the SCF E3 ubiquitin-protein ligase complex. FBXW7 participates in the degradation of a variety of oncoproteins and is deleted or mutated in many cancers. Simple variants in FBXW7 are seen in 3% of all tumors, including 9% of uterine and colorectal cancers, and 4% of skin tumors. In preclinical and clinical studies, FBXW7 variants may predict sensitivity to mTORC1 inhibitors.