TSC2 and neoplasm: Importantly, when injected subcutaneously into female SCID-beige mice, shRNA-Tsc2/Cdkn2a∆/∆ (n = 12 injections) and shRNA-Tsc2 + Cdkn2a (n = 16 injections) sphere-selected cells formed slowly growing tumours within 1–2 months (Fig. 1d).