Regulates a signal transduction pathway linking plasma membrane receptors to the assembly of focal adhesions and actin stress fibers. (Microbial infection) Glycosylated at Tyr-34 by Yersinia ruckeri toxin Afp18. Mono-O-GlcNAcylation by Afp18 inhibits RhoA activation by guanine nucleotide exchange factors and blocks RhoA signaling. Belongs to the small GTPase superfamily. Rho family.