RAB19 is a small GTPase that functions as a key regulator of intracellular membrane trafficking by cycling between inactive GDP-bound and active GTP-bound conformations to recruit downstream effectors 1. RAB19 coordinates cortical actin clearing and apical membrane partitioning through association with the RAB-GAP TBC1D4 and HOPS-tethering complex, a function essential for primary ciliogenesis in both polarized and nonpolarized cells 1. Beyond ciliogenesis, RAB19 participates in acrosome biogenesis, where it interacts with WDR38 and Golgi protein GM130 to facilitate vesicle formation and docking at the equatorial segment 2. RAB19 also serves as a GEF substrate for the TRAPPII complex 3. Disease relevance includes associations with azathioprine-induced pancreatic injury, with a genome-wide association study identifying rs2948386 in RAB19 showing significant association (OR=3.47, P=1.46E-8) 4. Additionally, RAB19 expression is regulated in gastric cancer through the miR-495-5p/RAB19 axis, where elevated RAB19 promotes cancer cell proliferation, migration, and invasion 5. RAB19 is also identified as a prognostic marker in oral squamous cell carcinoma within an immune score-based risk signature 6. These findings position RAB19 as a multifunctional membrane trafficking regulator with clinical significance in drug-induced injury and cancer progression.