TSC2 and neoplasm: Sirolimus, a highly specific inhibitor of mTORC1, can suppress the growth of spontaneously occurring renal tumours in a Tsc2+/− Eker rat model [6] and in Tsc1+/− and Tsc2+/− mice [7], as well as in TSC2-deficient xenograft tumours in immune-deficient mice [8].