Nevertheless, our findings confirmed not only that the minimal expression of AREG/EREG might identify wt KRAS tumours that have a high likelihood of resistance to Ctx but also suggested that the positive selection of Ctx-resistant tumour cells exhibiting AREG/EREG cross-suppression most likely has an important role in determining the emergence of Ctx resistance. The gene discussed is CYP27A1; the disease is neoplasm.