SKP2 and cancer: Like β-TrCP1, SKP2, another well-characterized F-box protein, acts as a classic oncogene which promotes proliferation and survival of cancer cells, mainly through targeted degradation of a number of tumour suppressive proteins, including p21 (ref. 34), p27 (refs 35, 36), p57 (ref. 37), p130 (ref. 38), FOXO1 (ref. 39), among many others40.