Second, the osteocalcin promoter contains a cis-acting element termed ose2, a binding site for the osteoblast transcriptional regulator Runx2, which has been implicated in cleidocranial dysplasia in humans and mice (Mundlos et al., 1995; Otto et al., 1997). The gene discussed is RUNX2; the disease is cleidocranial dysplasia 1.