REVIEW Regulation of translation initiation by FRAP/mTOR

Regulation of protein synthesis in eukaryotes plays a critical role in development, differentiation, cell cycle progression, cell growth, and apoptosis (Mathews et al. 2000). Translational control allows for a more rapid re-sponse than transcriptional modulation because no mRNA synthesis, processing, or transport is required, and can be used to coordinate gene expression in systems that lack transcriptional regulation, such as reticulo-cytes or platelets (Weyrich et al. 1998; Mathews et al. 2000). Translational control plays a particularly impor-tant role in early developmental processes, when local-ized translation is utilized to establish polarity (Wickens et al. 2000), and localized translation in neurons may be critical for learning and memory (e.g., Casadio et al