Following osteogenic treatment, overexpression of Ndrg1 blocked osteogenic differentiation, as indicated by the attenuated alkaline phosphatase (ALP) staining and alizarin red staining (Fig. 2B), and the decreased mRNA and protein levels of the osteogenic factors such as Runx2, osterix, ALP and osteopontin as compared to the infection of the control virus (mRNAs decreased by 45–68% and proteins decreased by 42–56%) (Fig. 2C, D). Here, SPP1 is linked to infection.