This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Translation, Subject name: Biochemistry
During eukaryotic protein synthesis, phosphorylation of which of the following is enhanced by insulin? 
Select and explain. 
A. eIF4E, B. eIF4G, C. eIFA, D. eIF2
B: eIF4G
Answer: B: eIF4G 
Explanation: Insulin phosphorylates both 4E-binding protein and eIF-4G. The 4F complex consists of eIF-4E (4E), eIF-4A, and eIF-4G. 4E is inactive when bound by one of a family of binding proteins (4E-BPs). Insulin and mitogenic growth polypeptides, or growth factors activate the PI3 kinase/AKT kinase pathways, which activate the mTOR kinase, and results in the phosphorylation of 4E-BP. Phosphorylated 4E-BP dissociates from 4E, and the latter is then able to form the 4F complex and bind to the mRNA cap.