Many genes involved in osteoblastic differentiation have been implicated in craniosynostosis, including RUNX2, Indian hedgehog, Twist1, fibroblast growth factors (FGFs) and FGFRs. 45Thus, following the detection of PC1 in our human craniosynostosis cell model, we proceeded to explore the functional role of PC1 in the cellular process of differentiation by focusing on its effect on the activation of RUNX2. The gene discussed is TWIST1; the disease is craniosynostosis.