NRG1 and neoplasm: De Boer et al (1997) showed that expression of different NRG1 isoforms varied in different cell layers of the normal and malignant bladder. In the normal urothelium, expression of NRG1α and NRG1β1 isoforms was highest in the differentiated superficial cells and NRG1α and NRG1β mRNA was detected in 90 and 61% of tumours, respectively, with a negative trend between NRG1β expression and survival (Memon et al, 2004). In contrast, Amsellem-Ouazana et al (2006) did not detect NRG1 in 5 normal bladder and 73 tumour samples.