Promotes endothelial cell sprouting and actin cytoskeletal reorganization. May be involved in angiogenesis. May function in Ca(2+) signaling. In vitro, interacts with calmodulin in a calcium-dependent manner. Most highly expressed in the endothelial lining of the blood vessels in uterus and heart. Lower levels found in spleen, lymph node, kidney and testis. Also found in cells with secretory function such as the islets of Langerhans, lobule/duct epithelium in the breast, bile duct epithelium in the liver, surface epithelium in the endometrial glands of the uterus, colon mucosa and acinar cells in the pancreas and the prostate. Belongs to the small GTPase superfamily. RGK family.