MTOR and central nervous system cancer: Additionally, mTOR phosphorylation has been demonstrated in many cancer lines, such as osteosarcoma, melanoma, hemangiosarcoma, mast cell tumor, breast adenocarcinoma, glioma, and lymphoma, by western blotting, and rapamycin, which is an mTOR inhibitor, is associated with decreased mTOR phosphorylation and cell viability (50, 55–58).