This result demonstrates that the efficacy of 5-FU may be enhanced by Chk1 inhibitors in CRC cell lines expressing APC truncations, although it should be noted that the 5-FU sensitivity of cells after over expression of wild type APC was not further enhanced by inhibition of Chk 1 (Supplementary Fig. S8C). The gene discussed is CHEK1; the disease is colorectal carcinoma.