MTOR and colorectal carcinoma: To further explore the mechanism through which rhein regulates mTOR in CRC cells, we analyzed mTOR protein stability by treatment with cycloheximide (CHX, a protein synthesis inhibitor) and pretreated HCT116 cells for 1, 2, and 3 h in the presence or absence of the proteasome inhibitor, MG132 (15 μM).