EIF4E and neoplasm: While 4EBP1 appears to exert tumor suppressor activity, since it blocks the oncoprotein eIF4E [19], inhibits cellular proliferation [20] and restricts tumor growth in genetically engineered mouse models of prostate [21] as well as head and neck squamous cell carcinoma (HNSCC) [22], pro-tumorigenic functions also have been reported for 4EBP1.