NRG1 and neoplasm: This may identify the presence of an NRG1–ERBB3/ERBB2 autocrine loop in these cases as in other tumour cell types (Gilmour et al, 2002; Venkateswarlu et al, 2002; Li et al, 2004; Sheng et al, 2010), and could indicate that very low levels of receptor expression may be sufficient for signalling.