SND1 (staphylococcal nuclease and tudor domain containing 1) is a multifunctional RNA-binding protein with significant roles in viral infection, cancer progression, and cellular metabolism. In SARS-CoV-2 infection, SND1 binds to negative-sense viral RNA at the 5' end and interacts with viral protein NSP9 to promote viral RNA synthesis and replication organelle formation 1. The protein functions as an oncoprotein in multiple cancer types, where it forms critical protein-protein interactions with MTDH in breast cancer progression and metastasis 2. In hepatocellular carcinoma, SND1 interacts with AEG-1, and this interaction is regulated by palmitoylation, affecting RISC complex activity and tumor suppressor expression 3. SND1 also plays a role in lipid metabolism through regulation of cholesterol homeostasis via SREBP2 activation 4. In melanoma, SND1-enriched exosomes facilitate lung metastasis by promoting CD47 sorting into exosomes, enabling immune evasion through the CD47-SIRPα axis and preventing macrophage-mediated phagocytosis 5. Additionally, SND1 participates in stress response pathways, interacting with FMRP in cellular stress conditions and contributing to stress granule formation 6. The protein's overexpression is associated with poor prognosis in various cancers, making it a potential therapeutic target.