Figure 1.

NRG–ErbB signaling pathway. Neuregulin-1 (NRG1) and NRG2 bind to ErbB3 and/or ErbB4, which in turn undergoes homo or heterodimerization and activates PI3K. PI3K then activates AKT and subsequently mTOR causing initiation of protein synthesis via the mTOR signaling pathway. mTOR phosphorylates and activates P70S6K which facilitates phosphorylation of small ribosomal protein 6 (S6) and eukaryotic translation initiation factor 4B (eIF4B) and leads to initiation of protein synthesis. Activated mTOR also causes phosphorylation and inactivation of eIF4EBP1, which release eIF4E and facilitates translation.