MEX3B is an RNA-binding protein that functions as a post-transcriptional regulator by binding to the 3' untranslated regions (UTRs) of target mRNAs and modulating their stability 12. The protein plays diverse roles across different biological contexts through its ability to destabilize specific target transcripts. In cancer immunotherapy resistance, MEX3B binds to HLA-A mRNA's 3' UTR, reducing HLA-A expression on tumor cell surfaces and enabling immune evasion by preventing T-cell recognition 2. In nasal epithelial cells, MEX3B regulates inflammation by binding to TGFBR3 mRNA and reducing its stability, thereby inhibiting TGF-β2-mediated collagen production and tissue fibrosis in eosinophilic chr15 rhinosinusitis 1. MEX3B also functions as a TLR3 coreceptor, with IL-37 suppressing its expression to modulate immune responses 3. In bone metabolism, MEX3B inhibits osteoclast formation by suppressing DC-STAMP mRNA levels, with its own expression being downregulated during osteoclast differentiation 4. Additionally, MEX3B regulates cellular organization through the Rap1 pathway, controlling phagocytosis and cell-cell interactions in Sertoli cells 5. Clinically, MEX3B expression is associated with cancer prognosis and immune cell infiltration patterns 6.