Involved in cell shape and neuronal morphogenesis, positively regulating the establishment and maintenance of dendritic spines (By similarity). Plays a role in cellular protein transport, including protein transport away from primary cilia (PubMed:23264467). May function via activation of RAC1 and PAK1 (By similarity). Homodimer (PubMed:23798443). Interacts with RAC1 (By similarity). Interacts (via N-terminus) with MYO5A, the interaction is required for its role in dendrite formation (PubMed:23798443). Interacts with RAB8A; interaction is dependent on the phosphorylation of RAB8A on 'Thr-72' (PubMed:29125462). Interacts with RAB10 and RAB12; interaction is dependent on the phosphorylation of 'Thr-73' on RAB10 and 'Ser-105' on RAB12 (By similarity). Belongs to the RILPL family.