Plays an important role in cell growth. Required to keep the uninucleated state. May be involved in the organization of the cytoskeleton which affects microtubule functions. Most likely RHO3 and RHO4 of S.cerevisiae regulate partially overlapping but different pathways. GTP + H2O = GDP + H(+) + phosphate Interacts with BEM4. Belongs to the small GTPase superfamily. Rho family. Leads to a fusion with RNC1.