STAU1 (staufen double-stranded RNA binding protein 1) is an RNA-binding protein that regulates mRNA stability, translation, and decay through recognition of double-stranded RNA structures. The protein mediates Staufen-mediated mRNA decay (SMD) by binding to STAU1-binding sites within 3'-UTRs of target mRNAs and interacting with the RNA helicase UPF1 to promote mRNA degradation 1. STAU1 forms dynamic cytoplasmic condensates that recruit and enhance translation of specific mRNAs, including MTOR mRNA, leading to mTOR pathway activation 2. The protein plays critical roles in cancer biology, exhibiting oncogenic characteristics in lung adenocarcinoma by modulating gene expression and alternative splicing patterns that affect cell proliferation, invasion, and migration 3. In neurodegeneration, STAU1 overabundance is a common pathological feature across multiple diseases including ALS, Alzheimer's, Parkinson's, and Huntington's disease 4. Excessive STAU1 levels drive mTOR hyperactivation and impair autophagy-lysosome function, contributing to disease pathogenesis 5. Additionally, STAU1 phosphorylation status regulates the balance between cell proliferation and apoptosis, with phosphomimicry at serine 20 triggering apoptosis in transformed cells 6. The protein also facilitates viral particle production for various viruses including HIV-1 and influenza.