RAB21 is a small GTPase that regulates intracellular membrane trafficking and vesicle transport. As a member of the Rab family, it cycles between inactive GDP-bound and active GTP-bound states to control vesicle formation, movement, and fusion 1. RAB21 plays critical roles in integrin trafficking and recycling, which is essential for cell adhesion, migration, and cytokinesis 23. During cancer cell migration, RAB21 interacts with specific adaptors like Swiprosin-1 to facilitate integrin endocytosis through clathrin-independent pathways 2. In macrophages, RAB21 serves as a general regulator of surface protein expression, including Fc gamma receptors, affecting phagocytosis and cellular identity 4. RAB21 also functions in autophagy by regulating SNARE-mediated autophagosome-lysosome fusion and modulates Golgi trafficking of cargo receptors. Clinically, RAB21 has dual significance in disease: it acts as a tumor suppressor in renal cell carcinoma through EGFR pathway regulation 5, while functioning as an oncogene in gliomas where its knockdown induces apoptosis 6. RAB21 variants are associated with obesity 7 and the protein is degraded through both ubiquitin-proteasome and autophagy-lysosome pathways 8.