By immunoblotting, there were increased levels of mTORC1 substrate p-4E-BP1 in PRCC-TFE3; KSP-Cre kidney tumor lysates compared to controls, though total 4E-BP1 levels were increased as well (Supplementary Fig. 4B) as has been seen previously in other mouse models with mTORC1 activation in the kidney20. This evidence concerns the gene PRCC and kidney neoplasm.