Rab proteins belong to the Ras small GTPase superfamily. The GTP-binding Rab3 subfamily has 4 known isoforms: 3A, 3B, 3C, and 3D (Schluter et al., 2004). These proteins are expressed in highest concentrations in brain and endocrine tissues and involved in regulated exocytosis of hormones and neurotransmitters (Coppola et al., 2002). Specifically, Rab3
