EIF3M (eukaryotic translation initiation factor 3 subunit M) is a non-core subunit of the eIF3 complex, which plays a pivotal role in eukaryotic translation initiation by bridging the 43S pre-initiation complex and eIF4F-bound mRNA 1. EIF3M functions as a component of the eIF3 complex involved in formation of cytoplasmic translation initiation complexes and ribosomal recycling 2. Additionally, EIF3M participates in mitochondria-associated translation regulation through K63 ubiquitination, wherein GPS2-mediated inhibition of ubiquitination controls the import-coupled translation of nuclear-encoded mitochondrial proteins 3. EIF3M also exhibits compartment-specific proteasomal interactions, with evidence of a hybrid proteasome variant where EIF3M substitutes for the structural subunit Rpn9 4. EIF3M deregulation is associated with multiple malignancies. Elevated EIF3M expression correlates with colon cancer progression and regulates tumorigenesis-related genes including MIF and MT2A 5. In prostate cancer, high EIF3M expression promotes c-Myc signaling activation and predicts biochemical recurrence; EIF3M knockdown suppresses prostate cancer cell growth 6. EIF3M is also a direct target of H19X-encoded microRNAs that regulate skeletal muscle mass through translation initiation factor abundance 7. Clinical significance includes EIF3M's potential as a therapeutic target in cancer treatment, though additional investigation of EIF3M-dependent mechanisms is needed 1.