RAB37 is a small GTPase that functions as a key regulator of intracellular membrane trafficking and autophagy. As a member of the Rab protein family, RAB37 cycles between inactive GDP-bound and active GTP-bound conformations to recruit downstream effectors responsible for vesicle formation, movement, and fusion 1. RAB37 acts as an organizer for autophagosome biogenesis in a GTP-dependent manner and is involved in retinal homeostasis through autophagy regulation 1. Mechanistically, RAB37 mediates the intracellular trafficking and exocytosis of multiple cargo proteins including IL-6, CHI3L1, TIMP1, ST2L, and PD-1 23456. Additionally, GDP-bound RAB37 exhibits a non-canonical function by interacting with STAT1 to sequester it in the cytosol, thereby suppressing type I interferon signaling 7. Clinically, RAB37 dysregulation correlates with poor cancer prognosis. Low RAB37 expression in gastric cancer promotes epithelial-mesenchymal transition and metastasis by reducing autophagic degradation of β-catenin 8. Conversely, elevated RAB37 expression in tumor-associated macrophages and T cells promotes an immunosuppressive tumor microenvironment through enhanced secretion of pro-tumoral cytokines and increased PD-1 membrane presentation, associating with chemotherapy and immunotherapy resistance 265.