MTOR and gastrointestinal stromal tumor: Given that Topo II inhibitors are currently used for therapy of STS [19,20,21,22] and taking into account that GIST were also previously shown to be sensitive to the Topo II inhibitors [23,24], we thought to examine whether inhibition of the PI3K/AKT/mTOR pathway might enhance their sensitivity to Topo II inhibitor, doxorubicin (DOX) via targeting of the molecular pathways involved in DNA DSB repair.