Updated publication reference for PubMed record(s): 25609615. Although the Mnks have been known for >15 years, their roles in the regulation of protein synthesis have remained obscure. Here we explore how BDNF stimulates protein synthesis in cortical neurons. Using a combination of pharmacological and genetic approaches, we show that this effect depends on MEK/ERK signaling and on the downstream kinase, Mnk1, which phosphorylates eIF4E. Translation initiation is mediated by the interaction of eIF4E with the m7GTP cap of mRNA and with eIF4G. The latter interaction is inhibited by the interactions of eIF4E with partner proteins such as CYFIP1, which together with its partner, FMRP acts as a translational repressor. We find that BDNF induces the release of CYFIP1 from eIF4E, and that this depends on Mnk1. Finally, using a novel combination of BONCAT and SILAC, we identify the a subset of proteins whose synthesis is upregulated by BDNF signalling via Mnk1 in neurons. The This subset of Mnk1-sensitive proteins are enriched for functions involved in neurotransmission and synaptic plasticity. Additionally, we find significant overlap between our subset of Mnk1 Mnk1-sensitive proteins and proteins encoded by known FMRP-binding mRNAs. Taken together, our data implicate Mnk1 as a key component of BDNF-mediated translational regulation in neurons.