RAB6B, also known as ras-related protein Rab-6B, belongs to Rab6 family of the small GTPase superfamily. The Rab6 subfamily consists of three different isoforms: Rab6A, Rab6A' and Rab6B. Both Rab6A and Rab6A' are ubiquitously expressed whereas Rab6B is predominantly expressed in brain. Rab6 is a key regulator in the retrograde transfer from endosomes via the Golgi to the ER and may function in retrograde tansport in neuronal cells.