MYO9B (MYR5) is a RHO GAP protein that stimulates RHOA GTPase activity, resulting in hydrolysis of RHOA bound GTP to GDP, and conversion of the active form of RHOA, RHOA:GTP, to the inactive form, RHOA:GDP (Post et al. 1998, Graf et al. 2000, Kong et al. 2015). MYO9B does not act on CDC42 and RAC1. The GAP activity of MYO9B is inhibited by binding to ROBO1 receptor activated by SLIT2 (Kong et al. 2015).