FGF23 and craniosynostosis: Beyond downregulation of TNAP, proposed mechanisms for these changes include TGF-β/BMP signalling (ERK1/2) and Wnt signalling [125, 201, 202], while cross-binding of FGF23 with FGFR2 and FGFR3 at the cranial sutures has also been proposed to contribute to craniosynostosis [203].