To understand how β-TrCP activity may be altered in different cancers with elevated expression of β-TrCP, we stably expressed the β-TrCP reporter in cell lines with variable expression levels of β-TrCP, as measured by western blotting, ranging from relatively low levels (U2OS) to relatively high levels (HeLa, NCI-H460) (Supplementary Fig. 5f). This evidence concerns the gene BTRC and cancer.