Fig. 1. Regulation of endochondral ossification by transcription factors. Sex-determining region Y (SRY)-box 9 (Sox9) and Sox5/6/9 promotes commitment of mesenchymal cells into chondrocytes and chondrocyte differentiation, while Sox9 negatively regulates the late stage of endochondral ossification. Myocyte-enhancer factor 2C (Mef2C), runt-related transcription factor 2/3 (Runx2/3) and osterix regulate hypertrophy of chondrocytes, and calcification and degradation of cartilage matrices. Histone deacetylase 4 (Hdac4) antagonizes function of Mef2c.