Small GTPase which cycles between an active GTP-bound and an inactive GDP-bound state (PubMed:15907487, PubMed:16034420). Involved in protein transport (PubMed:29425100). Plays a role in vesicular traffic. Mediates VEGFR2 endosomal trafficking to enhance VEGFR2 signaling (PubMed:29425100). Acts as a regulator of platelet alpha-granule release during activation and aggregation of platelets (By similarity).