Members of the large SOX family of transcription factors are widely conserved and at least 20 are found in mammals. Structurally SOX proteins exhibit a high mobility group (HMG) motif that binds the DNA minor groove. SOX family members are often found in multiprotein complexes that regulate their ability to affect transcription. SOX proteins play important roles in early development and are often used as markers to assess the differentiation of specific cell lineages.
SRY (Sex determining Region Y)-box 9 (SOX9) belongs to the SOX (SRY-like HMG box) family of transcription factors with diverse roles in development. SOX9 is expressed in mesenchymal progenitors that give rise to chondrocytes and osteoblasts. SOX9 is also expressed in the central nervous system, neural crest, intestine, pancreas, and testis. Mutations in SOX9 are associated with defects in sex determination, cartilage and bone development, as well as abnormalities of the heart, kidneys, brain, gut, and pancreas.