RUNX2 and craniosynostosis: Early onset of Runx2 expression in the cranial mesenchyme in transgenic mice resulted in craniosynostosis, ectopic bone formation, and limb defects (Maeno et al., 2011), whereas the proliferation of osteoblast progenitors is impaired due to the reduced expression of the direct Runx2 targets Fgfr2 and Fgfr3 in Runx2−/− mice (Kawane et al., 2018).