EPAS1 and dysplasia: Hypoxia-inducible factor-2α expression has not been studied in models of tumour carcinogenesis except in our work in the Barrett's metaplasia–dysplasia–adenocarcinoma sequence, where we showed that HIF-2α was expressed late in the sequence and was seen only in dysplasia and adenocarcinoma (Griffiths et al, 2007a).