HIF1A and neoplasm: Tumours in Vhl∆/∆Trp53∆/∆Rb1∆/∆Hif1a∆/∆ mice lacked the clear nuclear HIF-1α signal that was present in tumours from Vhl∆/∆Trp53∆/∆Rb1∆/∆ and Vhl∆/∆Trp53∆/∆Rb1∆/∆Hif2a∆/∆ mice when staining with an anti-HIF-1α antibody (Fig. 1d).