RABAC1 (Rab acceptor 1) is a four-pass transmembrane protein that functions as a general regulator of Rab GTPases involved in vesicle trafficking from the Golgi complex. RABAC1 mediates Rab GTPase interaction with SNARE complexes to control vesicle docking and fusion, while inhibiting GDI-mediated removal of Rab proteins from membranes 1. Beyond its canonical Golgi localization, an endogenous RABAC1 subpopulation resides at ER-mitochondria membrane contact sites, with ER retention sequences suggesting additional functional roles in the endoplasmic reticulum 2. Clinically, RABAC1 has emerged as a potential therapeutic target in cancer. In gastric cancer cells, RABAC1 directly interacts with and inhibits the anti-apoptotic protein BCL2A1, promoting caspase-3 activation and apoptosis while reducing cell proliferation, clonogenic survival, and invasion 3. In non-small cell lung cancer, RABAC1 was part of an invasion-associated four-gene signature that independently predicted patient survival across multiple cohorts 4. Lower RABAC1 expression correlated with poor prognosis in lung adenocarcinoma 5. Genetic association studies identified RABAC1 variants in transmission disequilibrium testing for suicide attempt, though this finding required replication 6. RABAC1 splicing fidelity remains stable with age but increases under mechanical stress 7.