TFE3 and kidney neoplasm: 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.