Ras homolog gene family, member A (RhoA) is a small GTPase that plays critical roles in several essential cell functions, such as migration, adhesion, proliferation, and gene expression. RhoA switches between a GTP-bound active form and a GDP-bound inactive form. The activated RhoA directly interacts with its downstream effectors, such as Rho kinase (ROCK) to regulate actomyosin dynamics, or mDia1 to control stress fiber and filopodia formation. The activity of RhoA is primarily regulated by guanine nucleotide exchange factors (GEFs), GTPase-activating protein (GAP), and guanine nucleotide-dissociation inhibitors (GDIs).