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. Calmodulin binding significantly decreases GTP binding. Binds ROCK1 (By similarity). By mitogens. Phosphorylated on tyrosine residues. Belongs to the small GTPase superfamily. RGK family.