MTOR and T-cell leukemia: T-cell leukemia cell lines and Drosophila melanogaster models of Notch induced tumorigenesis have demonstrated that Notch and Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) (upstream of mTOR) are linked via phosphatase and tensin homolog (PTEN), an upstream negative regulator of protein kinase B (AKT)/mTOR [17].