The small GTPases Rab are key regulators in vesicle trafficking .Essential for maintaining the integrity of the endosome-trans-Golgi network structure.Together with LRRK2, plays a role in the retrograde trafficking pathway for recycling proteins, such as mannose 6 phosphate receptor (M6PR), between lysosomes and the Golgi apparatus in a retromer-dependent manner.Recruits LRRK2 to the Golgi complex and stimulates LRRK2 kinase activity.