EPAS1 and neoplasm: Nuclear HIF-2α staining was present in tumours from Vhl∆/∆Trp53∆/∆Rb1∆/∆ and Vhl∆/∆Trp53∆/∆Rb1∆/∆Hif1a∆/∆ mice but absent in all tumours from Vhl∆/∆Trp53∆/∆Rb1∆/∆Hif2a∆/∆ mice.