The VPS9 ankyrin repeat protein (VARP) binds to the Rab21, a guanine nucleotide exchange factor that plays an essential role in endocytic trafficking. VARP localizes to early endosomes and is thought to regulate endosome dynamics. VARP also interacts with TI-VAMP/VAMP7, a vesicular SNARE that mediates an exocytic pathway that is crucial to neurite growth. Depletion of VARP by RNA interference impairs neurite growth, suggesting that VARP is a positive regulator of neurite growth.Synonyms: Ankyrin repeat domain-containing protein 27, VPS9 domain-containing protein