RUNX2 and aortic valve disorder: While runt-related transcription factor 2 (Runx2) is not normally expressed in the aortic valves and blood vessels, numerous studies have demonstrated the de novo expression of Runx2 associated with osteochondrogenic cell differentiation and the formation of cartilaginous and calcified bone-like lesions in aortic valve disease, diabetic calcifying lesions, and atherosclerotic plaques in humans and experimental animal models (21, 22, 24, 28–36).