MTOR and breast cancer: p70 ribosomal protein S6 kinase 1 (S6K1), an important downstream kinase of Akt-mTOR pathway, has been reported to play roles including tumor growth, chemoresistance and self-renewal ability in numerous of cancers such as leukemia, bladder cancer, colorectal carcinomas, neuroblastoma and breast cancer 9, 18-20.