RPTOR and breast carcinoma: Thus, immunoblotting of multiple mTORC1 core proteins and its downstream targets (mTOR, Raptor, p70S6K, rpS6 and 4E-BP1) revealed that the mTORC1 pathway is inhibited in matrix-deprived breast cancer cells (Figures 1C,D) which is suggestive of inhibition of global protein translation under matrix-detached stress.