ACTA2 and acute myeloid leukemia: In addition, mTOR activation, assessed by pS6 expression, was observed in both ACTA2+ or PMEL+ cells of TSC2−/− AML organoid graft cells, but not in the adjacent normal rat tissue or in TSC2+/+ or TSC2+/− organoid xenografts, indicating that metabolic activation was consistent with xenograft growth (Fig. 5h).