RHOBTB1 shares 80% sequence identity with RHOBTB2, with close to 95% identity in the GTPase domain (reviewed by Ji and Rivero 2016). Based on studies in RHOBTB2 (Manjarrez et al. 2014), as well as on the primary structure of the GTPase domain, RHOBTB1 is expected to bind to GTP, but not to cycle between GTP- and GDP-bound states. There are no known RHOBTB1 GAPs - DEBDC1B was reported to bind RHOBTB1 by Bagci et al. 2020, but its RHOBTB1-directed GAP activity has not been tested.