AKT1 and telomere syndrome: In addition to increased levels of cleaved caspase-3 and PARP in cancer cells treated with Dox in presence of AKT inhibitor, we also observed the increased numbers of apoptotic (e.g., Annexin V-positive cells) cells in RD rhabdomyosarcoma and GIST T-1R cells treated with combination of Dox and MK-2206 when compared to non-treated cells or cells treated with Dox alone (Figure S4), thereby revealing that AKT inhibition effectively sensitized STS and GIST cells to Dox treatment and induced apoptotic cell death.