RUNX2 is a member of the RUNX family of transcription factors. It is involved in osteoblast differentiation and skeletal morphogenesis. RUNX2 regulates the transcription of various genes including osteopontin, bone sialoprotein, and osteocalcin via binding to the core site of the enhancers or promoters. RUNX2 is crucial for the maturation of osteoblasts and both intramembranous and endochondral ossification. Mutations in RUNX2 have been associated with the bone development disorder cleidocranial dysplasia. RUNX2 is also abnormally expressed in various human cancers including prostate cancer and breast cancer. It plays an important role in migration, invasion, and bone metastasis of prostate and breast cancer cells.