RAB31 is a small GTPase that regulates intracellular membrane trafficking and plays significant roles in cancer progression. As a member of the RAS oncogene family, RAB31 controls ESCRT-independent exosome biogenesis by engaging flotillin proteins in lipid raft microdomains and recruiting TBC1D2B to prevent multivesicular endosome degradation 1. In cancer contexts, RAB31 is consistently upregulated across multiple tumor types including breast, gastric, and cervical cancers, where it promotes metastasis and chemotherapy resistance 234. Mechanistically, RAB31 enhances epithelial-mesenchymal transition through Twist1-mediated pathways and stabilizes oncoproteins like MAPK6 by preventing their degradation 34. The protein also facilitates fibrogenic extracellular vesicle release in hepatic stellate cells, amplifying liver fibrosis through glycolysis-dependent mechanisms 5. Additionally, RAB31 supports oncogenic translation programs by maintaining tRNA stability, particularly for leucine transport, which enables synthesis of cancer-promoting proteins including c-Myc and BCL2 6. These diverse functions establish RAB31 as both a prognostic biomarker and potential therapeutic target across multiple cancer types.