EIF4E and cancer: Another mechanism that explains the resistance to mTOR kinase inhibitors is that cancer cells downregulate the expression of 4E-BPs which leads to an increase in the eIF4E/4E-BP1 ratio, and it is this change in eIF4E/4E-BP1 stoichiometry that limits the sensitivity of cancer cells to catalytic site TOR inhibitors suggesting that the eIF4E/4E-BP1 ratio might act as a predictive marker for treatments using catalytic TOR inhibitors [169].