Cbfa1/Runx2 is a key transcription factor associated with osteoblast differentiation.This protein is a member of the RUNX family of transcription factors and has a Runt DNA-binding domain. It is essential for osteoblastic differentiation and skeletal morphogenesis and acts as a scaffold for nucleic acids and regulatory factors involved in skeletal gene expression. The protein can bind DNA both as a monomer or, with more affinity, as a subunit of a heterodimeric complex. Transcript variants of the gene that encode different protein isoforms result from the use of alternate promoters as well as alternate splicing.The RUNX2 transcription factor is the master regulator of osteoblast differentiation is required for chondrocyte hypertrophy .