AXIN2 and craniosynostosis: Mice deficient in Axin2, a negative regulator of canonical WNT signaling, exhibit craniosynostosis due to an increased proliferation of osteoblastic progenitors in the skull sutures [37], and haploid deficiency of β-catenin was shown to alleviate craniofacial bone defects caused by Axin2 deficiency [38].