Could be a regulatory protein, possibly participating in receptor-mediated signal transduction at the plasma membrane. Has guanine nucleotide-binding activity but undetectable intrinsic GTPase activity. Interacts with calmodulin in a Ca(2+)-dependent manner. Binds ROCK1. Most abundant in thymus, spleen, kidney, lung, and testis. Less abundant in heart, brain, liver and skeletal muscle. By mitogens. Phosphorylated on tyrosine residues. Belongs to the small GTPase superfamily. RGK family.