Anti-phospho 4E-BP1 (Ser83) serum, from rabbit

Eukaryotic translation initiation factor 4E-binding protein 1 (UniProt: Q13541; also known as 4E-BP1, eIF4E-binding protein 1, Phosphorylated heat- and acid-stable protein regulated by insulin 1, PHAS-I) is encoded by the EIF4EBP1 gene (Gene ID: 1978) in human. 4E-BP1 is a repressor of translation initiation that regulates EIF4E activity by preventing its assembly into the eIF4F complex. It mediates the regulation of protein translation by hormones, growth factors and other stimuli that signal through the MAP kinase and mTORC1 pathways. 4E-BP1 is phosphorylated on serine and threonine residues in response to insulin, EGF, and PDGF. Non-phosphorylated 4E-BP1 bind strongly to eIF4E; however, phosphorylated 4E-BP1 does not bind to eIF4E. 4E-BP1 is reported to act as an inhibitory factor of tumor cells survival and proliferation because of its role as a negative regulator of cap-dependent translation. Although 4E-BP1 serves as a well-characterized substrate of mTORC1, an mTOR-independent phosphorylation of 4E-BP1 has been also been suggested to be associated with the mTOR kinase inhibitor resistance in cancer cells. (Ref.: Shang, ZF et al (2012). Cell Cycle 11(18): 3463 3471).