Small GTPases of the Rho family are critical regulators of various cellular functions including actin cytoskeleton organization, activation of kinase cascades, mitogenesis, transcriptional activation and stimulation of DNA synthesis. Rho proteins cycle between a biologically active GTP-bound state and an inactive GDP-bound state. Rho guanine nucleotide exchange factor (GEF) has a crucial role in activating small GTPase by exchange GDP for GTP. ARGEF16 is one of the multiple GEF members. Although the specific function of this protein is not known yet, it is thought to be involved in protein-protein and protein-lipid interactions.