EIF4EBP1 and neoplasm: The ineffectiveness of mTORC1 inhibitors in tumor treatment23–25 and in functional reactivation of ESR1 may be related to incomplete inhibition of 4E-BP1 phosphorylation, because rapamycin was known to potently inhibit phosphorylation of S6RP but not that of 4E-BP126,44,59,60.