To compare the extent of Cre-mediated deletion of Vhl, Trp53, Rb1, Hif1a, and Hif2a we conducted quantitative real-time PCR using primers to specifically amplify floxed exons of each gene as well as non-floxed exons of the Vhl, Trp53, and Hif2a genes (which served as normalisation controls) from genomic DNA from cortex samples from non-Cre mice (WT cortex), as well as tumours from Vhl∆/∆Trp53∆/∆Rb1∆/∆, Vhl∆/∆Trp53∆/∆Rb1∆/∆Hif1a∆/∆, and Vhl∆/∆Trp53∆/∆Rb1∆/∆Hif2a∆/∆ mice. This evidence concerns the gene RB1 and neoplasm.