Although the details of the involvement of wildtype and mutant APC and functional redundancy of APC2 in the responsiveness of downstream signaling to WNT ligand in CRCs harboring APC loss of function remain unknown, our findings revealed a critical role for WNT ligand in the activation and enrichment of CSCs in the 5-FU-treated CRC tumors. The gene discussed is APC; the disease is colorectal carcinoma.