Involved in cell shape and neuronal morphogenesis, positively regulating the establishment and maintenance of dendritic spines (PubMed:19812310). Plays a role in cellular protein transport, including protein transport away from primary cilia (By similarity). May function via activation of RAC1 and PAK1 (PubMed:19812310). Homodimer (By similarity). Interacts (via N-terminus) with MYO5A, the interaction is required for its role in dendrite formation (PubMed:19812310). Interacts with RAC1 (PubMed:19812310). Interacts with RAB8A; interaction is dependent on the phosphorylation of RAB8A on 'Thr-72' (By similarity). Interacts with RAB10 and RAB12; interaction is dependent on the phosphorylation of 'Thr-73' on RAB10 and 'Ser-105' on RAB12 (By similarity).