SMAD1 and neural tube defect: In this study, we observed an increased gene expression of Bmp2, Bmp4, Smad1, Smad5, Smad8, and Runx2, the phosphorylation of Smad1/5/8, and the activation of Runx2 in Li2CO3-induced NTD mouse embryonic neural tissues and in mNSCs exposed to Li2CO3 or an inositol- free medium, and that inositol-free condition had more evident effects.