EREG and neoplasm: Although Baker’s finding that increased AREG/EREG expression was positively associated with an enhanced sensitivity to Ctx, and other studies likewise agree with the notion that stimulators of the EGFR pathway (e.g., EGFR ligands) are expected to associate with an increased likelihood of disease control in patients receiving Ctx (Khambata-Ford et al, 2007; Jacobs et al, 2009), none of the above-mentioned studies have established a causal relationship between the expression status of AREG/EREG and Ctx responsiveness in wt KRAS tumour cells.