FBXW7 and colorectal carcinoma: Consistent with CRC cell lines, we further confirmed that Fbxw7 deficiency confers higher tolerance to 5-FU, a DNA damaging agent; the IC50 of fbxw7 mutant mini-guts was significantly higher than controls (5.7 versus 2.6 μmol/l 5-FU, respectively) (Figure 3c).