4E-BP1 (eukaryotic initiation factor 4E-binding protein 1) is a key regulator of protein translation and plays a crucial role in controlling the assembly of the eIF4F complex, which is essential for cap-dependent translation initiation. It is the most widely expressed and well-characterized member of the 4E-BP family in mammalian cells. When active, 4E-BP1 binds to eIF4E, preventing its interaction with eIF4G and thereby inhibiting the formation of the eIF4F complex, which is necessary for the translation of many oncogenic mRNAs with structured 5鈥?UTRs. This mechanism is critical in suppressing tumor development, as hyperactive eIF4E-dependent translation contributes to the upregulation of pro-tumorigenic genes in cancer cells. The activity of 4E-BP1 is regulated by various signaling pathways, including the PI3K/AKT/mTOR pathway, which can lead to its phosphorylation and inactivation, allowing eIF4E to promote translation. Reactivating 4E-BP1 through mTOR inhibition or other mechanisms has been shown to have tumor-suppressive effects.