TWIST1 and craniosynostosis: The PCR array results were further validated by real-time quantitative PCR for seven of the most highly expressed and relevant genes in craniosynostosis: when induced by stiffness and cultured with growth medium, expression of five genes increased in cells from fused sutures, BMP6, MSX2, TWIST and WNT2 (p < 0.05) and TGFβ, (p < 0.01) and no stiffness-mediated increases in gene expression were observed in cells from patent sutures (Fig. 5D).