FBXW7 and colon carcinoma: To confirm that c-Myc degradation was mediated by Fbw7 in response to hypoxia signaling, we used the human colon carcinoma HCT116 cell line and a derivative cell line, HCT116 Fbw7−/−, in which both alleles of the Fbw7 gene have been disrupted by homologous recombination [16].