Regulates the GDP/GTP exchange reaction of the Rho proteins by inhibiting the dissociation of GDP from them, and the subsequent binding of GTP to them (PubMed:7512369, PubMed:8356058). Regulates reorganization of the actin cytoskeleton mediated by Rho family members (PubMed:8262133). {ECO:0000269|PubMed:7512369, ECO:0000269|PubMed:8262133, ECO:0000269|PubMed:8356058}. This is the function of ENSG00000111348 (ARHGDIB, Rho GDP dissociation inhibitor beta).