RAB3C is a small GTPase belonging to the Rab3 family that regulates intracellular membrane trafficking by cycling between inactive GDP-bound and active GTP-bound forms 1. The protein localizes to chromosome 5 and is expressed in brain, placenta, and lung tissues 1. RAB3C functions in regulated exocytosis, controlling vesicular transport and membrane fusion across multiple cellular contexts 2. In spermatogenesis, RAB3C localizes to the manchette structure, postacrosomal region, neck, and midpiece, playing a critical role in sperm head and tail morphogenesis; delocalization of RAB3C is associated with morphological sperm defects linked to SEPT14 mutations 3. RAB3C also functions in endocytosis and autophagy of TGF-β receptor 2, with deficiency exacerbating thoracic aortic aneurysm development in Marfan syndrome models 4. Clinically, RAB3C is upregulated in adrenal medullary hyperplasia associated with secondary hypertension 5 and in non-small cell lung cancer, where elevated expression via the circ_0070659/miR-377/RAB3C axis promotes tumor proliferation, migration, and invasion 6. RAB3C overexpression has been observed in various cancers including gliomas and colon cancers, correlating with decreased survival and advanced pathological stage 7. These findings position RAB3C as a multifunctional regulator of membrane dynamics with significant pathophysiological implications.