Small GTP-binding protein which cycles between a GDP-bound inactive and a GTP-bound active form. Involved in EGFR and CHRM3 signaling pathways through stimulation of PLCE1. May play a role in cytoskeletal rearrangements and regulate cell spreading through activation of the effector TNIK. May regulate membrane vesiculation in red blood cells (By similarity). GTP + H2O = GDP + H(+) + phosphate Interacts with PLCE1. Interacts with SGSM1, SGSM2 and SGSM3. The GTP-bound form of RAP2B interacts with RUNDC3A (By similarity). Associated with red blood cells-released vesicles. The effector domain mediates the interaction with RUNDC3A. Palmitoylated. Unlike RAP2A and RAP2C, palmitoylation of RAP2B is not required for association with recycling endosome membranes and activation of TNIK. Belongs to the small GTPase superfamily. Ras family.